Understanding cursors and counters
I have this process running whenever the Delete button is pressed. It overwrites the value of mobile in ICT_PEEP.
If i add a row to the ICT_PHONE table and then remove it this process removes the value in mobile but if i add rows then delete one the value in mobile stays as expected but if i Delete the other the value is still there??? and it shouldn't be. If i add another row. just one then delete it it removes the value in mobile? i don't see how this is the case?
add 1 remove one fine
add 2 remove 2 not fine
ad 1 remove 1 works even after the above?
I can't work out where i am going wrong?
any ideas?
DECLARE
cursor c8 is
select
ID
from ICT_PHONE
where PERSON_ID = :P9_PERSON_ID;
ID_N NUMBER;
ctr NUMBER := 0;
NHY VARCHAR2(3) := ' ';
BEGIN
OPEN c8;
LOOP
FETCH c8 INTO ID_N;
EXIT WHEN c8%NOTFOUND;
ctr := ctr + 1;
END LOOP;
CLOSE c8;
IF ctr = 1 THEN
UPDATE ICT_PEEP SET MOBILE = NHY WHERE ICT_PEEP.ID = :P9_PERSON_ID;
END IF;
ctr :=0;
END;
I'm not sure if I understood everything, but based on my quick look at the code.
Are you sure that PERSON_ID is unique in the ICT_PHONE table? What happens if your cursor loop returns two or more rows, the UPDATE will never be executed.
Usewwv_flow.debug('count: '||ctr);(you have to run in debug mode) or a
RAISE_APPLICATION_ERROR(-20999,'Count: '||ctr);to find out what's going on in your process.
BTW, you are really writing blanks into a VARCHAR2 column? That's not really a good practice...
Patrick
My APEX Blog: http://inside-apex.blogspot.com
The ApexLib Framework: http://apexlib.sourceforge.net
The APEX Builder Plugin: http://sourceforge.net/projects/apexplugin/
Similar Messages
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PL/SQL 101 : Cursors and SQL Projection
PL/SQL 101 : Cursors and SQL Projection
This is not a question, it's a forum article, in reponse to the number of questions we get regarding a "dynamic number of columns" or "rows to columns"
There are two integral parts to an SQL Select statement that relate to what data is selected. One is Projection and the other is Selection:-
Selection is the one that we always recognise and use as it forms the WHERE clause of the select statement, and hence selects which rows of data are queried.
The other, SQL Projection is the one that is less understood, and the one that this article will help to explain.
In short, SQL Projection is the collective name for the columns that are Selected and returned from a query.
So what? Big deal eh? Why do we need to know this?
The reason for knowing this is that many people are not aware of when SQL projection comes into play when you issue a select statement. So let's take a basic query...
First create some test data...
create table proj_test as
select 1 as id, 1 as rn, 'Fred' as nm from dual union all
select 1,2,'Bloggs' from dual union all
select 2,1,'Scott' from dual union all
select 2,2,'Smith' from dual union all
select 3,1,'Jim' from dual union all
select 3,2,'Jones' from dual
... and now query that data...
SQL> select * from proj_test;
ID RN NM
1 1 Fred
1 2 Bloggs
2 1 Scott
2 2 Smith
3 1 Jim
3 2 Jones
6 rows selected.
OK, so what is that query actually doing?
To know that we need to consider that all queries are cursors and all cursors are processed in a set manner, roughly speaking...
1. The cursor is opened
2. The query is parsed
3. The query is described to know the projection (what columns are going to be returned, names, datatypes etc.)
4. Bind variables are bound in
5. The query is executed to apply the selection and identify the data to be retrieved
6. A row of data is fetched
7. The data values from the columns within that row are extracted into the known projection
8. Step 6 and 7 are repeated until there is no more data or another condition ceases the fetching
9. The cursor is closed
The purpose of the projection being determined is so that the internal processing of the cursor can allocate memory etc. ready to fetch the data into. We won't get to see that memory allocation happening easily, but we can see the same query being executed in these steps if we do it programatically using the dbms_sql package...
CREATE OR REPLACE PROCEDURE process_cursor (p_query in varchar2) IS
v_sql varchar2(32767) := p_query;
v_cursor number; -- A cursor is a handle (numeric identifier) to the query
col_cnt integer;
v_n_val number; -- numeric type to fetch data into
v_v_val varchar2(20); -- varchar type to fetch data into
v_d_val date; -- date type to fetch data into
rec_tab dbms_sql.desc_tab; -- table structure to hold sql projection info
dummy number;
v_ret number; -- number of rows returned
v_finaltxt varchar2(100);
col_num number;
BEGIN
-- 1. Open the cursor
dbms_output.put_line('1 - Opening Cursor');
v_cursor := dbms_sql.open_cursor;
-- 2. Parse the cursor
dbms_output.put_line('2 - Parsing the query');
dbms_sql.parse(v_cursor, v_sql, dbms_sql.NATIVE);
-- 3. Describe the query
-- Note: The query has been described internally when it was parsed, but we can look at
-- that description...
-- Fetch the description into a structure we can read, returning the count of columns that has been projected
dbms_output.put_line('3 - Describing the query');
dbms_sql.describe_columns(v_cursor, col_cnt, rec_tab);
-- Use that description to define local datatypes into which we want to fetch our values
-- Note: This only defines the types, it doesn't fetch any data and whilst we can also
-- determine the size of the columns we'll just use some fixed sizes for this example
dbms_output.put_line(chr(10)||'3a - SQL Projection:-');
for j in 1..col_cnt
loop
v_finaltxt := 'Column Name: '||rpad(upper(rec_tab(j).col_name),30,' ');
case rec_tab(j).col_type
-- if the type of column is varchar2, bind that to our varchar2 variable
when 1 then
dbms_sql.define_column(v_cursor,j,v_v_val,20);
v_finaltxt := v_finaltxt||' Datatype: Varchar2';
-- if the type of the column is number, bind that to our number variable
when 2 then
dbms_sql.define_column(v_cursor,j,v_n_val);
v_finaltxt := v_finaltxt||' Datatype: Number';
-- if the type of the column is date, bind that to our date variable
when 12 then
dbms_sql.define_column(v_cursor,j,v_d_val);
v_finaltxt := v_finaltxt||' Datatype: Date';
-- ...Other types can be added as necessary...
else
-- All other types we'll assume are varchar2 compatible (implicitly converted)
dbms_sql.DEFINE_COLUMN(v_cursor,j,v_v_val,2000);
v_finaltxt := v_finaltxt||' Datatype: Varchar2 (implicit)';
end case;
dbms_output.put_line(v_finaltxt);
end loop;
-- 4. Bind variables
dbms_output.put_line(chr(10)||'4 - Binding in values');
null; -- we have no values to bind in for our test
-- 5. Execute the query to make it identify the data on the database (Selection)
-- Note: This doesn't fetch any data, it just identifies what data is required.
dbms_output.put_line('5 - Executing the query');
dummy := dbms_sql.execute(v_cursor);
-- 6.,7.,8. Fetch the rows of data...
dbms_output.put_line(chr(10)||'6,7 and 8 Fetching Data:-');
loop
-- 6. Fetch next row of data
v_ret := dbms_sql.fetch_rows(v_cursor);
-- If the fetch returned no row then exit the loop
exit when v_ret = 0;
-- 7. Extract the values from the row
v_finaltxt := null;
-- loop through each of the Projected columns
for j in 1..col_cnt
loop
case rec_tab(j).col_type
-- if it's a varchar2 column
when 1 then
-- read the value into our varchar2 variable
dbms_sql.column_value(v_cursor,j,v_v_val);
v_finaltxt := ltrim(v_finaltxt||','||rpad(v_v_val,20,' '),',');
-- if it's a number column
when 2 then
-- read the value into our number variable
dbms_sql.column_value(v_cursor,j,v_n_val);
v_finaltxt := ltrim(v_finaltxt||','||to_char(v_n_val,'fm999999'),',');
-- if it's a date column
when 12 then
-- read the value into our date variable
dbms_sql.column_value(v_cursor,j,v_d_val);
v_finaltxt := ltrim(v_finaltxt||','||to_char(v_d_val,'DD/MM/YYYY HH24:MI:SS'),',');
else
-- read the value into our varchar2 variable (assumes it can be implicitly converted)
dbms_sql.column_value(v_cursor,j,v_v_val);
v_finaltxt := ltrim(v_finaltxt||',"'||rpad(v_v_val,20,' ')||'"',',');
end case;
end loop;
dbms_output.put_line(v_finaltxt);
-- 8. Loop to fetch next row
end loop;
-- 9. Close the cursor
dbms_output.put_line(chr(10)||'9 - Closing the cursor');
dbms_sql.close_cursor(v_cursor);
END;
SQL> exec process_cursor('select * from proj_test');
1 - Opening Cursor
2 - Parsing the query
3 - Describing the query
3a - SQL Projection:-
Column Name: ID Datatype: Number
Column Name: RN Datatype: Number
Column Name: NM Datatype: Varchar2
4 - Binding in values
5 - Executing the query
6,7 and 8 Fetching Data:-
1 ,1 ,Fred
1 ,2 ,Bloggs
2 ,1 ,Scott
2 ,2 ,Smith
3 ,1 ,Jim
3 ,2 ,Jones
1 ,3 ,Freddy
1 ,4 ,Fud
9 - Closing the cursor
PL/SQL procedure successfully completed.
So, what's really the point in knowing when SQL Projection occurs in a query?
Well, we get many questions asking "How do I convert rows to columns?" (otherwise known as a pivot) or questions like "How can I get the data back from a dynamic query with different columns?"
Let's look at a regular pivot. We would normally do something like...
SQL> select id
2 ,max(decode(rn,1,nm)) as nm_1
3 ,max(decode(rn,2,nm)) as nm_2
4 from proj_test
5 group by id
6 /
ID NM_1 NM_2
1 Fred Bloggs
2 Scott Smith
3 Jim Jones
(or, in 11g, use the new PIVOT statement)
but many of these questioners don't understand it when they say their issue is that, they have an unknown number of rows and don't know how many columns it will have, and they are told that you can't do that in a single SQL statement. e.g.
SQL> insert into proj_test (id, rn, nm) values (1,3,'Freddy');
1 row created.
SQL> select id
2 ,max(decode(rn,1,nm)) as nm_1
3 ,max(decode(rn,2,nm)) as nm_2
4 from proj_test
5 group by id
6 /
ID NM_1 NM_2
1 Fred Bloggs
2 Scott Smith
3 Jim Jones
... it's not giving us this 3rd entry as a new column and we can only get that by writing the expected columns into the query, but then what if more columns are added after that etc.
If we look back at the steps of a cursor we see again that the description and projection of what columns are returned by a query happens before any data is fetched back.
Because of this, it's not possible to have the query return back a number of columns that are based on the data itself, as no data has been fetched at the point the projection is required.
So, what is the answer to getting an unknown number of columns in the output?
1) The most obvious answer is, don't use SQL to try and pivot your data. Pivoting of data is more of a reporting requirement and most reporting tools include the ability to pivot data either as part of the initial report generation or on-the-fly at the users request. The main point about using the reporting tools is that they query the data first and then the pivoting is simply a case of manipulating the display of those results, which can be dynamically determined by the reporting tool based on what data there is.
2) The other answer is to write dynamic SQL. Because you're not going to know the number of columns, this isn't just a simple case of building up a SQL query as a string and passing it to the EXECUTE IMMEDIATE command within PL/SQL, because you won't have a suitable structure to read the results back into as those structures must have a known number of variables for each of the columns at design time, before the data is know. As such, inside PL/SQL code, you would have to use the DBMS_SQL package, just like in the code above that showed the workings of a cursor, as the columns there are referenced by position rather than name, and you have to deal with each column seperately. What you do with each column is up to you... store them in an array/collection, process them as you get them, or whatever. They key thing though with doing this is that, just like the reporting tools, you would need to process the data first to determine what your SQL projection is, before you execute the query to fetch the data in the format you want e.g.
create or replace procedure dyn_pivot is
v_sql varchar2(32767);
-- cursor to find out the maximum number of projected columns required
-- by looking at the data
cursor cur_proj_test is
select distinct rn
from proj_test
order by rn;
begin
v_sql := 'select id';
for i in cur_proj_test
loop
-- dynamically add to the projection for the query
v_sql := v_sql||',max(decode(rn,'||i.rn||',nm)) as nm_'||i.rn;
end loop;
v_sql := v_sql||' from proj_test group by id order by id';
dbms_output.put_line('Dynamic SQL Statement:-'||chr(10)||v_sql||chr(10)||chr(10));
-- call our DBMS_SQL procedure to process the query with it's dynamic projection
process_cursor(v_sql);
end;
SQL> exec dyn_pivot;
Dynamic SQL Statement:-
select id,max(decode(rn,1,nm)) as nm_1,max(decode(rn,2,nm)) as nm_2,max(decode(rn,3,nm)) as nm_3 from proj_test group by id order by id
1 - Opening Cursor
2 - Parsing the query
3 - Describing the query
3a - SQL Projection:-
Column Name: ID Datatype: Number
Column Name: NM_1 Datatype: Varchar2
Column Name: NM_2 Datatype: Varchar2
Column Name: NM_3 Datatype: Varchar2
4 - Binding in values
5 - Executing the query
6,7 and 8 Fetching Data:-
1 ,Fred ,Bloggs ,Freddy
2 ,Scott ,Smith ,
3 ,Jim ,Jones ,
9 - Closing the cursor
PL/SQL procedure successfully completed.
... and if more data is added ...
SQL> insert into proj_test (id, rn, nm) values (1,4,'Fud');
1 row created.
SQL> exec dyn_pivot;
Dynamic SQL Statement:-
select id,max(decode(rn,1,nm)) as nm_1,max(decode(rn,2,nm)) as nm_2,max(decode(rn,3,nm)) as nm_3,max(decode(rn,4,nm)) as nm_4 from proj_test group by id order by id
1 - Opening Cursor
2 - Parsing the query
3 - Describing the query
3a - SQL Projection:-
Column Name: ID Datatype: Number
Column Name: NM_1 Datatype: Varchar2
Column Name: NM_2 Datatype: Varchar2
Column Name: NM_3 Datatype: Varchar2
Column Name: NM_4 Datatype: Varchar2
4 - Binding in values
5 - Executing the query
6,7 and 8 Fetching Data:-
1 ,Fred ,Bloggs ,Freddy ,Fud
2 ,Scott ,Smith , ,
3 ,Jim ,Jones , ,
9 - Closing the cursor
PL/SQL procedure successfully completed.
Of course there are other methods, using dynamically generated scripts etc. (see Re: 4. How do I convert rows to columns?), but the above simply demonstrates that:-
a) having a dynamic projection requires two passes of the data; one to dynamically generate the query and another to actually query the data,
b) it is not a good idea in most cases as it requires code to handle the results dynamically rather than being able to simply query directly into a known structure or variables, and
c) a simple SQL statement cannot have a dynamic projection.
Most importantly, dynamic queries prevent validation of your queries at the time your code is compiled, so the compiler can't check that the column names are correct or the tables names, or that the actual syntax of the generated query is correct. This only happens at run-time, and depending upon the complexity of your dynamic query, some problems may only be experienced under certain conditions. In effect you are writing queries that are harder to validate and could potentially have bugs in them that would are not apparent until they get to a run time environment. Dynamic queries can also introduce the possibility of SQL injection (a potential security risk), especially if a user is supplying a string value into the query from an interface.
To summarise:-
The projection of an SQL statement must be known by the SQL engine before any data is fetched, so don't expect SQL to magically create columns on-the-fly based on the data it's retrieving back; and, if you find yourself thinking of using dynamic SQL to get around it, just take a step back and see if what you are trying to achieve may be better done elsewhere, such as in a reporting tool or the user interface.
Other articles in the PL/SQL 101 series:-
PL/SQL 101 : Understanding Ref Cursors
PL/SQL 101 : Exception Handlingexcellent article. However there is one thing which is slightly erroneous. You don't need a type to be declared in the database to fetch the data, but you do need to declare a type;
here is one of my unit test scripts that does just that.
DECLARE
PN_CARDAPPL_ID NUMBER;
v_Return Cci_Standard.ref_cursor;
type getcardapplattrval_recordtype
Is record
(cardappl_id ci_cardapplattrvalue.cardappl_ID%TYPE,
tag ci_cardapplattrvalue.tag%TYPE,
value ci_cardapplattrvalue.value%TYPE
getcardapplattrvalue_record getcardapplattrval_recordtype;
BEGIN
PN_CARDAPPL_ID := 1; --value must be supplied
v_Return := CCI_GETCUSTCARD.GETCARDAPPLATTRVALUE(
PN_CARDAPPL_ID => PN_CARDAPPL_ID
loop
fetch v_return
into getcardapplattrvalue_record;
dbms_output.put_line('Cardappl_id=>'||getcardapplattrvalue_record.cardappl_id);
dbms_output.put_line('Tag =>'||getcardapplattrvalue_record.tag);
dbms_output.put_line('Value =>'||getcardapplattrvalue_record.value);
exit when v_Return%NOTFOUND;
end loop;
END; -
Cursor and Update rows based on value/date
SQL Server 2012
Microsoft SQL Server Management Studio
11.0.3128.0
Microsoft Analysis Services Client Tools
11.0.3128.0
Microsoft Data Access Components (MDAC)
6.1.7601.17514
Microsoft MSXML 3.0 4.0 5.0 6.0
Microsoft Internet Explorer
9.11.9600.16518
Microsoft .NET Framework
4.0.30319.18408
Operating System
6.1.7601
The objective of this is to test the Cursor and use it on a production environment after this is fixed. What I would like to do is update rows in a column i duplicated originally called 'HiredDate' from AdventureWorks2012 HumanResources.Employee table. I
made a duplicate column called 'DateToChange' and would like to change it based on a date I have picked, which returns normally 2 results (i.e. date is '04/07/2003'). The code runs but will not change both dates. It did run however with an error but changed
only 1 of the 2 rows because it said ['nothing available in next fetch'].
The code to add the columns and perform the query to get the results I am running this against:
-- ADD column 'DateToChange'
ALTER TABLE [HumanResources].[Employee] ADD DateToChange Date NOT NULL;
-- Copy 'HireDate' data to 'DateToChange'
UPDATE HumanResources.Employee SET DateToChange = HireDate;
-- Change 'DateToChange' to NOT NULL
ALTER TABLE [HumanResources].[Employee] ALTER COLUMN DateToChange Date NOT NULL;
SELECT BusinessEntityID,HireDate, CONVERT( char(10),[DateToChange],101) AS [Formatted Hire Date]
FROM HumanResources.Employee
WHERE [DateToChange] = '04/07/2003';
Code:
USE AdventureWorks2012;
GO
-- Holds output of the CURSOR
DECLARE @EmployeeID INT
DECLARE @HiredDate DATETIME
DECLARE @HiredModified DATETIME
DECLARE @ChangeDateTo DATETIME
--Declare cursor
-- SCROLL CURSOR ALLOWS "for extra options" to pul multiple records: i.e. PRIOR, ABSOLUTE ##, RELATIVE ##
DECLARE TestCursor CURSOR SCROLL FOR
-- SELECT statement of what records going to be used by CURSOR
-- Assign the query to the cursor.
SELECT /*HumanResources.Employee.BusinessEntityID, HumanResources.Employee.HireDate,*/ CONVERT( char(10),[DateToChange],101) AS [Formatted Hire Date]
FROM HumanResources.Employee
WHERE DateToChange = '01/01/1901'
/*ORDER BY HireDate DESC*/ FOR UPDATE OF [DateToChange];
-- Initiate CURSOR and load records
OPEN TestCursor
-- Get first row from query
FETCH NEXT FROM TestCursor
INTO @HiredModified
-- Logic to tell the Cursor while "@@FETCH_STATUS" 0 the cursor has successfully fetched the next record.
WHILE (@@FETCH_STATUS = 0 AND @@CURSOR_ROWS = -1)
BEGIN
FETCH NEXT FROM TestCursor
IF (@HiredModified = '04/07/2003')/*05/18/2006*/
-- Sets @HiredModifiedDate data to use for the change
SELECT @ChangeDateTo = '01/01/1901'
UPDATE HumanResources.Employee
SET [DateToChange] = @ChangeDateTo --'01/01/1901'
FROM HumanResources.Employee
WHERE CURRENT OF TestCursor;
END
-- CLOSE CURSOR
CLOSE TestCursor;
-- Remove any references held by cursor
DEALLOCATE TestCursor;
GO
This query is run successfully but it does not produce the desired results to change the dates
04/07/2003 to 01/01/1901.
I would like the query to essentially be able to run the initial select statement, and then update and iterate through the returned results while replacing the necessary column in each row.
I am also open to changes or a different design all together.
For this query I need:
1. To narrow the initial set of information
2. Check if the information returned, in particular a date, is before [i.e. this current month minus 12 months or
12 months before current month]
3. Next replace the dates with the needed date
[Haven't written this out yet but it will need to be done]
4. After all this is done I will then need to update a column on each row:
if the 'date' is within 12 months to 12 months from the date checked
NOTE: I am new to TSQL and have only been doing this for a few days, but I will understand or read up on what is explained if given enough information. Thank you in advance for anyone who may be able to help.The first thing you need to do is forget about cursors. Those are rarely needed. Instead you need to learn the basics of the tsql language and how to work with data in sets. For starters, your looping logic is incorrect. You open
the cursur and immediately fetch the first row. You enter the loop and the first thing in the loop does what? Fetches another row. That means you have "lost" the values from the first row fetched. You also do not test the success of
that fetch but immediately try to use the fetched value. In addition, your cursor includes the condition "DateToChange = '01/01/1901' " - by extension you only select rows where HireDate is Jan 1 1901. So the value fetched into @HiredModified will
never be anything different - it will always be Jan 1 1901. The IF logic inside your loop will always evaluate to FALSE.
But forget all that. In words, tell us what you are trying to do. It seems that you intend to add a new column to a table - one that is not null (ultimately) and is set to a particular value based on some criteria. Since you intend the
column to be not null, it is simpler to just add the column as not null with a default. Because you are adding the column, the assumption is that you need to set the appropriate value for EVERY row in the table so the actual default value can be anything.
Given the bogosity of the 1/1/1901 value, why not use this as your default and then set the column based on the Hiredate afterwards. Simply follow the alter table statement with an update statement. I don't really understand what your logic
or goal is, but perhaps that will come with a better description. In short:
alter table xxx add DateToChange date default '19010101'
update xxx set DateToChange = HireDate where [some unclear condition]
Lastly, you should consider wrapping everything you do in a transaction so that you recover from any errors. In a production system, you should consider making a backup immediately before you do anything - strongly consider and have a good reason not
to do so if that is your choice (and have a recovery plan just in case). -
OCI doc says Cursor and Nested table have the same bind type SQLT_RSET but they don't
5 Binding and Defining in OCI
PL/SQL REF CURSORs and Nested Tables in OCI
says SQLT_RSET is passed for the dty parameter.
If I use SQLT_RSET for the return value of a function that returns a table and pass a statement handle's address for the OCI parameter data pointer, I expected that the statement handle will be instantiated as a result of executing the function on which I can further perform fetch, similar to a cursor. But it throws exception PLS-00382: expression is of wrong type ORA-06550: line 2, column 3. Is the above documentation wrong?
From the OCI header file I see that for varray and nested table it mentions to use SQLT_NCO. I could find no example in the OCI documentation on how to pass or receive as return value a nested value when using SQLT_NCO.
Please help before I shoot myself.So the Nested table I quoted in the doc is not actually used to mean a table type below?
create type t_resultsetdata as object (
i int, d decimal, c varchar(10)
create type t_nested_resultsetdata as table of t_resultsetdata;
create function Blah return t_nested_resultsetdata is . . .
For this you are saying to use SQL_NTY and not SQL_NCO. Can you tell where this usage is documented, because ocidfn.h says
#define SQLT_NTY 108
/* named object type */
#define SQLT_NCO 122
/* named collection type (varray or nested table) */
Another question - Because of the original document I said I followed, I thought I could treat cursor and nested table similarly in the calling application, i.e. I could repeatedly do a fetch on the OCIStmt* which will be bound for nested table. Now from what you say I understand I can't really bind a OCIStmt* for nested table but have an object type. That means it will get all the data of that collection in one go, right? LIke I said, lack of examples is making this tough. I don't want to look into OCI source code, as that will be too much. -
Possible deadlock: transactions, cursors, and sequences...
Hello,
After making recent changes to our database in response to a previous issue (bug found and patched in BDB; local code fixed by removing both DB_TXN_SNAPSHOT and DB_MULTIVERSION) we've come across a possible deadlock.
BACKGROUND:
This database has been running for over a year in production and I've never seen a hard deadlock. We use the default deadlock detection engine internal to BDB, transactions, and our code supports the processing of deadlocks and subsequent retries and final abandonment when necessary. The transactions in question involve cursors and sequences; we're using cursors to flip through entries in an existing database, and should no match be found for an update, we insert a new record. Before doing so, we grab the "next ID" (primary key) from a sequence we have (attached, as all sequences are, to its own different DB, done on advice from online docs: "For this reason, it is often preferable for sequence objects to be stored in their own database.") and finally insert the new record.
This is a 64-bit Linux machine. There were 4 operational threads at the time; all were waiting on pthread conditions. As I understand it, deadlocks should have been internally detected and returning DB_LOCK_DEADLOCK to us somewhere? Since we're using the default lock detection engine and firing it constantly, we should not require an Nth thread to monitor the lock tables and manually reject deadlocked transactions, etc?
I wasn't sure what to do when the deadlock occured, but I found some forum posts referencing a db_stat -Co and ran it, along with grabbing a core dump which I still have available. I've reverted the DB binary to older DB_MULTIVERSION code as I work on figuring this out, but if there's something else crucial I should have done, I can run the new code again and wait for another deadlock to happen to run additional diagnostics.
Any ideas or assistance is appreciated. Thank you.
DEADLOCK INFORMATION:
THREAD 2: Attempting to 'get' an asset.
(gdb) bt
#0 0x00002aec07e27496 in pthread_cond_wait@@GLIBC_2.3.2 () from /lib64/libpthread.so.0
#1 0x00002aec078ddeed in __db_pthread_mutex_lock () from /usr/local/BerkeleyDB.4.7/lib/libdb_cxx-4.7.so
#2 0x00002aec078dda8b in __db_tas_mutex_lock () from /usr/local/BerkeleyDB.4.7/lib/libdb_cxx-4.7.so
#3 0x00002aec0795b8f1 in __lock_get_internal () from /usr/local/BerkeleyDB.4.7/lib/libdb_cxx-4.7.so
#4 0x00002aec0795bc42 in __lock_get () from /usr/local/BerkeleyDB.4.7/lib/libdb_cxx-4.7.so
#5 0x00002aec07987d94 in __db_lget () from /usr/local/BerkeleyDB.4.7/lib/libdb_cxx-4.7.so
#6 0x00002aec07914625 in __ham_get_meta () from /usr/local/BerkeleyDB.4.7/lib/libdb_cxx-4.7.so
#7 0x00002aec07908d4b in __hamc_get () from /usr/local/BerkeleyDB.4.7/lib/libdb_cxx-4.7.so
#8 0x00002aec07979e8a in __dbc_get () from /usr/local/BerkeleyDB.4.7/lib/libdb_cxx-4.7.so
#9 0x00002aec0797aa0d in __dbc_pget () from /usr/local/BerkeleyDB.4.7/lib/libdb_cxx-4.7.so
#10 0x00002aec0798654b in __dbc_pget_pp () from /usr/local/BerkeleyDB.4.7/lib/libdb_cxx-4.7.so
#11 0x00002aec078d4dd7 in Dbc::get () from /usr/local/BerkeleyDB.4.7/lib/libdb_cxx-4.7.so
THREAD 5: Attempting to 'set' an asset.
(gdb) bt
#0 0x00002aec07e27496 in pthread_cond_wait@@GLIBC_2.3.2 () from /lib64/libpthread.so.0
#1 0x00002aec078ddeed in __db_pthread_mutex_lock () from /usr/local/BerkeleyDB.4.7/lib/libdb_cxx-4.7.so
#2 0x00002aec078dda8b in __db_tas_mutex_lock () from /usr/local/BerkeleyDB.4.7/lib/libdb_cxx-4.7.so
#3 0x00002aec079d0c45 in __seq_get () from /usr/local/BerkeleyDB.4.7/lib/libdb_cxx-4.7.so
#4 0x00002aec078dd02e in DbSequence::get () from /usr/local/BerkeleyDB.4.7/lib/libdb_cxx-4.7.so
THREAD 6: Attempting to 'set' an asset.
(gdb) bt
#0 0x00002aec07e27496 in pthread_cond_wait@@GLIBC_2.3.2 () from /lib64/libpthread.so.0
#1 0x00002aec078ddeed in __db_pthread_mutex_lock () from /usr/local/BerkeleyDB.4.7/lib/libdb_cxx-4.7.so
#2 0x00002aec078dda8b in __db_tas_mutex_lock () from /usr/local/BerkeleyDB.4.7/lib/libdb_cxx-4.7.so
#3 0x00002aec0795b8f1 in __lock_get_internal () from /usr/local/BerkeleyDB.4.7/lib/libdb_cxx-4.7.so
#4 0x00002aec0795bc42 in __lock_get () from /usr/local/BerkeleyDB.4.7/lib/libdb_cxx-4.7.so
#5 0x00002aec07987d94 in __db_lget () from /usr/local/BerkeleyDB.4.7/lib/libdb_cxx-4.7.so
#6 0x00002aec079893ee in __db_new () from /usr/local/BerkeleyDB.4.7/lib/libdb_cxx-4.7.so
#7 0x00002aec0798bb7e in __db_poff () from /usr/local/BerkeleyDB.4.7/lib/libdb_cxx-4.7.so
#8 0x00002aec07918eb3 in __ham_add_el () from /usr/local/BerkeleyDB.4.7/lib/libdb_cxx-4.7.so
#9 0x00002aec07907fe1 in __hamc_put () from /usr/local/BerkeleyDB.4.7/lib/libdb_cxx-4.7.so
#10 0x00002aec0797b6e5 in __dbc_put () from /usr/local/BerkeleyDB.4.7/lib/libdb_cxx-4.7.so
#11 0x00002aec0796ecde in __db_put () from /usr/local/BerkeleyDB.4.7/lib/libdb_cxx-4.7.so
#12 0x00002aec07985e6c in __db_put_pp () from /usr/local/BerkeleyDB.4.7/lib/libdb_cxx-4.7.so
#13 0x00002aec078d395c in Db::put () from /usr/local/BerkeleyDB.4.7/lib/libdb_cxx-4.7.so
THREAD 7: Attempting to 'set' an asset.
(gdb) bt
#0 0x00002aec07e27496 in pthread_cond_wait@@GLIBC_2.3.2 () from /lib64/libpthread.so.0
#1 0x00002aec078ddeed in __db_pthread_mutex_lock () from /usr/local/BerkeleyDB.4.7/lib/libdb_cxx-4.7.so
#2 0x00002aec078dda8b in __db_tas_mutex_lock () from /usr/local/BerkeleyDB.4.7/lib/libdb_cxx-4.7.so
#3 0x00002aec0795b8f1 in __lock_get_internal () from /usr/local/BerkeleyDB.4.7/lib/libdb_cxx-4.7.so
#4 0x00002aec0795bc42 in __lock_get () from /usr/local/BerkeleyDB.4.7/lib/libdb_cxx-4.7.so
#5 0x00002aec07987d94 in __db_lget () from /usr/local/BerkeleyDB.4.7/lib/libdb_cxx-4.7.so
#6 0x00002aec07915b6a in __ham_lock_bucket () from /usr/local/BerkeleyDB.4.7/lib/libdb_cxx-4.7.so
#7 0x00002aec07915dc7 in __ham_get_cpage () from /usr/local/BerkeleyDB.4.7/lib/libdb_cxx-4.7.so
#8 0x00002aec079075f9 in __ham_lookup () from /usr/local/BerkeleyDB.4.7/lib/libdb_cxx-4.7.so
#9 0x00002aec07908f9f in __hamc_get () from /usr/local/BerkeleyDB.4.7/lib/libdb_cxx-4.7.so
#10 0x00002aec07979e8a in __dbc_get () from /usr/local/BerkeleyDB.4.7/lib/libdb_cxx-4.7.so
#11 0x00002aec07984045 in __db_get () from /usr/local/BerkeleyDB.4.7/lib/libdb_cxx-4.7.so
#12 0x00002aec079d0374 in __seq_update () from /usr/local/BerkeleyDB.4.7/lib/libdb_cxx-4.7.so
#13 0x00002aec079d0c29 in __seq_get () from /usr/local/BerkeleyDB.4.7/lib/libdb_cxx-4.7.so
#14 0x00002aec078dd02e in DbSequence::get () from /usr/local/BerkeleyDB.4.7/lib/libdb_cxx-4.7.so
=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
Lock REGINFO information:
Lock Region type
5 Region ID
env/__db.005 Region name
0x2b8dbff65000 Original region address
0x2b8dbff65000 Region address
0x2b8dbff65138 Region primary address
0 Region maximum allocation
0 Region allocated
Region allocations: 225009 allocations, 0 failures, 0 frees, 1 longest
REGION_JOIN_OK Region flags
=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
Locks grouped by object:
Locker Mode Count Status ----------------- Object ---------------
808cfad0 READ 1 HELD db1 page 0
808cfad3 READ 2 HELD db1 page 0
808cfad5 READ 1 HELD db1 page 0
33 READ 1 HELD db1 handle 0
22 READ 1 HELD db2 handle 0
18 READ 1 HELD db3 handle 0
808cfad5 READ 1 HELD db1 page 3906
808cfad3 READ 1 HELD db1 page 6300
808cfad3 WRITE 1 HELD db1 page 6300
808cfad0 READ 1 HELD db1 page 8272
808cfabe WRITE 2 HELD db4 page 82387
808cfad3 WRITE 1 HELD db4 page 42879
808cfad3 WRITE 1 HELD db4 page 42878
808cfad3 WRITE 1 HELD db4 page 42877
808cfad3 WRITE 1 HELD db4 page 42874
808cfad3 WRITE 1 HELD db4 page 42873
808cfad3 WRITE 1 HELD db4 page 42872
808cfad3 WRITE 1 HELD db4 page 42901
808cfad3 WRITE 1 HELD db4 page 42897
808cfad3 WRITE 1 HELD db4 page 42882
808cfad3 WRITE 1 HELD db4 page 42881
808cfad3 WRITE 1 HELD db4 page 42880
808cfad3 WRITE 1 HELD db4 page 42894
808cfad3 WRITE 1 HELD db4 page 43797
1a READ 1 HELD db3sequence handle 0
1c READ 1 HELD db5 handle 0
20 READ 1 HELD db6 handle 0
24 READ 1 HELD db7 handle 0
808cfad3 READ 13 HELD db4 page 0
808cfabe READ 2 HELD db4 page 0
808cfabe WRITE 1 WAIT db4 page 0
808cfad5 READ 1 WAIT db4 page 0
26 READ 1 HELD db4 handle 0
808cfabe READ 2 HELD db4sequence page 0
808cfad0 READ 1 HELD db4sequence page 0
28 READ 1 HELD db4sequence handle 0
808cfabe READ 3 HELD db8 page 0
2a READ 1 HELD db8 handle 0
808cfabe READ 4 HELD db9 page 0
808cfad0 READ 1 HELD db9 page 0
808cfad3 READ 14 HELD db9 page 0
808cfad5 READ 1 HELD db9 page 0
808cfabe READ 1 HELD db4sequence page 2
808cfabe WRITE 1 HELD db4sequence page 2
808cfad0 READ 1 WAIT db4sequence page 2
2e READ 1 HELD db9 handle 0
808cfabe WRITE 2 HELD db9 page 1
808cfad3 READ 2 HELD db1sequence page 0
35 READ 1 HELD db1sequence handle 0
808cfad3 READ 1 HELD db1sequence page 2
808cfad3 WRITE 1 HELD db1sequence page 2
808cfad5 READ 1 HELD db9 page 2833
808cfad0 WRITE 1 HELD db9 page 7946
808cfad3 WRITE 14 HELD db9 page 8250
808cfabe WRITE 3 HELD db8 page 13301What else could be causing this in terms of the application having a resource locked? I can say that there are no other running threads doing anything related to BDB at all - they are all in similar "no work, sleep until we get some" calls, with the exception being the main thread which is sitting in sigwait(). What types of things could the application be doing that would prevent all 4 BDB threads from being able to obtain mutexes that are internal to them and not accessible to the application?
Other thoughts:
* On a fifth thread, from time to time, txn_checkpoint() is called. Could this have been left in an unclean state?
* If DB_RMW is used incorrectly, could lock order be compromised? We are not using CDS, so do we need to specify DB_WRITECURSOR to our db->cursor() calls? We do not; we only provide DB_RMW to pget() calls at present.
* Why is the thread attempting to call sequence->get also deadlocked? The sequence is in its own database - is it waiting on a more global "locker manager" mutex at a high level?
As I don't see how anything we do can directly control BDB's locking strategies, my only thought is that we're making a programming error to force BDB to lock things in an incorrect order in a way that prevents deadlock detection from occuring. Is this possible? Mainly the only thing changing here was our replacing DB_TXN_SNAPSHOT with the appropriate DB_RMW flags when needed, which is why I'm thinking we did something wrong here, but I'm not sure what.
I'll continue investigation, but any ideas you have in terms of appropriate directions would be helpful. I'll also work on reproducing this if I can by working backwards from the stack information. Thanks.
Later thought: Why is 808cfad3 not waiting on anything even though stack clearly shows it (thread 5, I'm guessing) in pthread_cond_wait? Can a transaction enter a wait state without showing up in db_stat output?
Thanks!
Edited by: user10542315 on Sep 11, 2009 1:21 PM
Edited by: user10542315 on Sep 11, 2009 2:52 PM -
I want to make a textfield non editable with blinking cursor,and the text is input from a custom keypad....
Please Help me.
I want to make a numpad of my own from which i can set the text but i want the user to tap in between the text..You seem to stop the while loop to run the following code, then the program ends. Are you running this using the "continuous run" button????
You need one big while loop containing the acquisition, then you build up the history data in a shift register. Clicking "save" will save the data, but not stop the loop.
Why did you place a time-control in the FOR loop??? This is just post-processing so it should just do it without any delays. I don't understand the logic in the FOR loop. You are appending arrays, but then you delete the first element at each iteraction constantly trimming data from the beginning of the appended array. Then you autoindex at the output tunnel heavily duplicating all data. Ths make s no sense!
Can you explain how you want you data saved?
Message Edited by altenbach on 12-16-2005 11:20 AM
LabVIEW Champion . Do more with less code and in less time . -
when to use cursor and when to use refcursor....
REF CURSORS are documented, just like CURSORS:
"You use cursor variables (REF CURSORS) to pass query result sets between PL/SQL stored subprograms and various clients."
http://asktom.oracle.com/pls/asktom/f?p=100:11:0::::P11_QUESTION_ID:2067669642079
http://download.oracle.com/docs/cd/B19306_01/appdev.102/b14261/sqloperations.htm#sthref1398
PL/SQL 101 : Understanding Ref Cursors
I suggest you do a few quick searches from the doc home and take a bit time to read, you'll find lots of examples and explanations:
http://www.oracle.com/pls/db102/homepage
or
http://www.oracle.com/pls/db112/homepage
By the way, you forgot to ask:
"when to use implicit cursor and when to use explicit cursor."
That is explained here (and you should read that as well):
http://asktom.oracle.com/pls/asktom/f?p=100:11:0::::P11_QUESTION_ID:1544606261686
http://asktom.oracle.com/pls/asktom/f?p=100:11:0::::P11_QUESTION_ID:1205168148688
and memorize 'The Mantra' ;) -
Help with if statement in cursor and for loop to get output
I have the following cursor and and want to use if else statement to get the output. The cursor is working fine. What i need help with is how to use and if else statement to only get the folderrsn that have not been updated in the last 30 days. If you look at the talbe below my select statement is showing folderrs 291631 was updated only 4 days ago and folderrsn 322160 was also updated 4 days ago.
I do not want these two to appear in my result set. So i need to use if else so that my result only shows all folderrsn that havenot been updated in the last 30 days.
Here is my cursor:
/*Cursor for Email procedure. It is working Shows userid and the string
You need to update these folders*/
DECLARE
a_user varchar2(200) := null;
v_assigneduser varchar2(20);
v_folderrsn varchar2(200);
v_emailaddress varchar2(60);
v_subject varchar2(200);
Cursor c IS
SELECT assigneduser, vu.emailaddress, f.folderrsn, trunc(f.indate) AS "IN DATE",
MAX (trunc(fpa.attemptdate)) AS "LAST UPDATE",
trunc(sysdate) - MAX (trunc(fpa.attemptdate)) AS "DAYS PAST"
--MAX (TRUNC (fpa.attemptdate)) - TRUNC (f.indate) AS "NUMBER OF DAYS"
FROM folder f, folderprocess fp, validuser vu, folderprocessattempt fpa
WHERE f.foldertype = 'HJ'
AND f.statuscode NOT IN (20, 40)
AND f.folderrsn = fp.folderrsn
AND fp.processrsn = fpa.processrsn
AND vu.userid = fp.assigneduser
AND vu.statuscode = 1
GROUP BY assigneduser, vu.emailaddress, f.folderrsn, f.indate
ORDER BY fp.assigneduser;
BEGIN
FOR c1 IN c LOOP
IF (c1.assigneduser = v_assigneduser) THEN
dbms_output.put_line(' ' || c1.folderrsn);
else
dbms_output.put(c1.assigneduser ||': ' || 'Overdue Folders:You need to update these folders: Folderrsn: '||c1.folderrsn);
END IF;
a_user := c1.assigneduser;
v_assigneduser := c1.assigneduser;
v_folderrsn := c1.folderrsn;
v_emailaddress := c1.emailaddress;
v_subject := 'Subject: Project for';
END LOOP;
END;
The reason I have included the folowing table is that I want you to see the output from the select statement. that way you can help me do the if statement in the above cursor so that the result will look like this:
emailaddress
Subject: 'Project for ' || V_email || 'not updated in the last 30 days'
v_folderrsn
v_folderrsn
etc
[email protected]......
Subject: 'Project for: ' Jim...'not updated in the last 30 days'
284087
292709
[email protected].....
Subject: 'Project for: ' Kim...'not updated in the last 30 days'
185083
190121
190132
190133
190159
190237
284109
286647
294631
322922
[email protected]....
Subject: 'Project for: Joe...'not updated in the last 30 days'
183332
183336
[email protected]......
Subject: 'Project for: Sam...'not updated in the last 30 days'
183876
183877
183879
183880
183881
183882
183883
183884
183886
183887
183888
This table is to shwo you the select statement output. I want to eliminnate the two days that that are less than 30 days since the last update in the last column.
Assigneduser....Email.........Folderrsn...........indate.............maxattemptdate...days past since last update
JIM......... jim@ aol.com.... 284087............. 9/28/2006.......10/5/2006...........690
JIM......... jim@ aol.com.... 292709............. 3/20/2007.......3/28/2007............516
KIM......... kim@ aol.com.... 185083............. 8/31/2004.......2/9/2006............. 928
KIM...........kim@ aol.com.... 190121............. 2/9/2006.........2/9/2006.............928
KIM...........kim@ aol.com.... 190132............. 2/9/2006.........2/9/2006.............928
KIM...........kim@ aol.com.... 190133............. 2/9/2006.........2/9/2006.............928
KIM...........kim@ aol.com.... 190159............. 2/13/2006.......2/14/2006............923
KIM...........kim@ aol.com.... 190237............. 2/23/2006.......2/23/2006............914
KIM...........kim@ aol.com.... 284109............. 9/28/2006.......9/28/2006............697
KIM...........kim@ aol.com.... 286647............. 11/7/2006.......12/5/2006............629
KIM...........kim@ aol.com.... 294631............. 4/2/2007.........3/4/2008.............174
KIM...........kim@ aol.com.... 322922............. 7/29/2008.......7/29/2008............27
JOE...........joe@ aol.com.... 183332............. 1/28/2004.......4/23/2004............1585
JOE...........joe@ aol.com.... 183336............. 1/28/2004.......3/9/2004.............1630
SAM...........sam@ aol.com....183876.............3/5/2004.........3/8/2004.............1631
SAM...........sam@ aol.com....183877.............3/5/2004.........3/8/2004.............1631
SAM...........sam@ aol.com....183879.............3/5/2004.........3/8/2004.............1631
SAM...........sam@ aol.com....183880.............3/5/2004.........3/8/2004.............1631
SAM...........sam@ aol.com....183881.............3/5/2004.........3/8/2004.............1631
SAM...........sam@ aol.com....183882.............3/5/2004.........3/8/2004.............1631
SAM...........sam@ aol.com....183883.............3/5/2004.........3/8/2004.............1631
SAM...........sam@ aol.com....183884.............3/5/2004.........3/8/2004............ 1631
SAM...........sam@ aol.com....183886.............3/5/2004.........3/8/2004............ 1631
SAM...........sam@ aol.com....183887.............3/5/2004.........3/8/2004............ 1631
SAM...........sam@ aol.com....183888.............3/5/2004.........3/8/2004............ 1631
PAT...........pat@ aol.com.....291630.............2/23/2007.......7/8/2008............ 48
PAT...........pat@ aol.com.....313990.............2/27/2008.......7/28/2008............28
NED...........ned@ aol.com.....190681.............4/4/2006........8/10/2006............746
NED...........ned@ aol.com......95467.............6/14/2006.......11/6/2006............658
NED...........ned@ aol.com......286688.............11/8/2006.......10/3/2007............327
NED...........ned@ aol.com.....291631.............2/23/2007.......8/21/2008............4
NED...........ned@ aol.com.....292111.............3/7/2007.........2/26/2008............181
NED...........ned@ aol.com.....292410.............3/15/2007.......7/22/2008............34
NED...........ned@ aol.com.....299410.............6/27/2007.......2/27/2008............180
NED...........ned@ aol.com.....303790.............9/19/2007.......9/19/2007............341
NED...........ned@ aol.com.....304268.............9/24/2007.......3/3/2008............ 175
NED...........ned@ aol.com.....308228.............12/6/2007.......12/6/2007............263
NED...........ned@ aol.com.....316689.............3/19/2008.......3/19/2008............159
NED...........ned@ aol.com.....316789.............3/20/2008.......3/20/2008............158
NED...........ned@ aol.com.....317528.............3/25/2008.......3/25/2008............153
NED...........ned@ aol.com.....321476.............6/4/2008.........6/17/2008............69
NED...........ned@ aol.com.....322160.............7/3/2008.........8/21/2008............4
MOE...........moe@ aol.com.....184169.............4/5/2004.......12/5/2006............629
[email protected]/27/2004.......3/8/2004............1631
How do I incorporate a if else statement in the above cursor so the two days less than 30 days since last update are not returned. I do not want to send email if the project have been updated within the last 30 days.
Edited by: user4653174 on Aug 25, 2008 2:40 PManalytical functions: http://download-west.oracle.com/docs/cd/B10501_01/server.920/a96540/functions2a.htm#81409
CASE
http://download.oracle.com/docs/cd/B10501_01/appdev.920/a96624/02_funds.htm#36899
http://download.oracle.com/docs/cd/B10501_01/appdev.920/a96624/04_struc.htm#5997
Incorporating either of these into your query should assist you in returning the desired results. -
Hi All
So in general why would we use a cursor and a for loop to do update in a stored procedure?
Why wouldnt we just use a single update statement ?
is there compelling reason for using a cursor and a for loop: I am reading some code from a co-worker that the business logic for the select (set need to be updated) is complex but the update logic is simple (just set a flag to (0 or 1 or 2 or 3 or 4).
But eventually the select come down to a key (row_id) so I re-write it using just a single sql statement.
The size of the main table is about 2.6 to 3million rows
Any thoughts on that??
The code below I just do a google for cursor for update example in case for something to play with
-Thanks for all your input
create table f (a number, b varchar2(10));
insert into f values (5,'five');
insert into f values (6,'six');
insert into f values (7,'seven');
insert into f values (8,'eight');
insert into f values (9,'nine');
commit;
create or replace procedure wco as
cursor c_f is
select a,b from f where length(b) = 5 for update;
v_a f.a%type;
v_b f.b%type;
begin
open c_f;
loop
fetch c_f into v_a, v_b;
exit when c_f%notfound;
update f set a=v_a*v_a where current of c_f;
end loop;
close c_f;
end;
exec wco;
select * from f;
drop table f;
drop procedure wco;
Joining multiple tables
create table numbers_en (
id_num number primary key,
txt_num varchar2(10)
insert into numbers_en values (1, 'one' );
insert into numbers_en values (2, 'two' );
insert into numbers_en values (3, 'three');
insert into numbers_en values (4, 'four' );
insert into numbers_en values (5, 'five' );
insert into numbers_en values (6, 'six' );
create table lang (
id_lang char(2) primary key,
txt_lang varchar2(10)
insert into lang values ('de', 'german');
insert into lang values ('fr', 'french');
insert into lang values ('it', 'italian');
create table translations (
id_num references numbers_en,
id_lang references lang,
txt_trans varchar2(10) not null
insert into translations values (1, 'de', 'eins' );
insert into translations values (1, 'fr', 'un' );
insert into translations values (2, 'it', 'duo' );
insert into translations values (3, 'de', 'drei' );
insert into translations values (3, 'it', 'tre' );
insert into translations values (4, 'it', 'quattro');
insert into translations values (6, 'de', 'sechs' );
insert into translations values (6, 'fr', 'six' );
declare
cursor cur is
select id_num,
txt_num,
id_lang,
txt_lang,
txt_trans
from numbers_en join translations using(id_num)
left join lang using(id_lang)
for update of translations.txt_trans;
rec cur%rowtype;
begin
for rec in cur loop
dbms_output.put (
to_char (rec.id_num , '999') || ' - ' ||
rpad (rec.txt_num , 10 ) || ' - ' ||
rpad(nvl(rec.txt_trans, ' '), 10 ) || ' - ' ||
rec.id_lang || ' - ' ||
rpad (rec.txt_lang , 10 )
if mod(rec.id_num,2) = 0 then
update translations set txt_trans = upper(txt_trans)
where current of cur;
dbms_output.put_line(' updated');
else
dbms_output.new_line;
end if;
end loop;
end;
/Edited by: xwo0owx on Apr 25, 2011 11:23 AMAdding my sixpence...
PL/SQL is not that different from a SQL perspective than any other SQL client language like Java or C# or C/C++. PL/SQL simply integrates the 2 languages a heck of a lot better and far more transparent than the others. But make no mistake in that PL/SQL is also a "client" language from a SQL perspective. The (internal) calls PL/SQL make to the SQL engine, are the same (driver) calls made to the SQL engine when using Java and C and the others.
So why a cursor and loops in PL/SQL? For the same reason you have cursors and loops in all these other SQL client languages. There are the occasion that you need to pull data from the SQL engine into the local language to perform some very funky and complex processing that is not possible using the SQL language.
The danger is using client cursor loop processing as the norm - always pulling rows into the client language and crunching it there. This is not very performant. And pretty much impossible to scale. Developers in this case views the SQL language as a mere I/O interface for reading and writing rows. As they would use the standard file I/O read() and write() interface calls.
Nothing could be further from the truth. SQL is a very advance and sophisticated data processing language. And it will always be faster than having to pull rows to a client language and process them there. However, SQL is not Turing complete. It is not the procedural type language that most other languages we use, are. For that reason there are things that we cannot do in SQL. And that should be the only reason for using the client language, like PL/SQL or the others, to perform row crunching using a client cursor loop. -
The query below will return values in the form of
bu seq eligible
22 2345 Y
22 2345 N
22 1288 N
22 1458 Y
22 1458 N
22 1234 Y
22 1333 N
What I am trying to accomplish is to loop through the records returned.
for each seq if there is a 'N' in the eligible column return no record for that seq
eg seq 2345 has 'Y' and 'N' thus no record should be returned.
seq 1234 has only a 'Y' then return the record
seq 1333 has 'N' so return no record.
How would I accomplish this with a ref Cursor and pass the values to the front end application.
Procedure InvalidNOs(io_CURSOR OUT T_CURSOR)
IS
v_CURSOR T_CURSOR;
BEGIN
OPEN v_CURSOR FOR
' select bu, seq, eligible ' ||
' from (select bu, seq, po, tunit, tdollar,eligible,max(eligible) over () re ' ||
' from (select bu, seq, po, tunit, tdollar,eligible ' ||
' from ( ' ||
' select bu, seq, po, tunit, tdollar, eligible, sum(qty) qty, sum(price*qty) dollars ' ||
' from ' ||
' ( select /*+ use_nl(t,h,d,s) */ ' ||
' h.business_unit_id bu, h.edi_sequence_id seq, d.edi_det_sequ_id dseq, ' ||
' s.edi_size_sequ_id sseq, h.po_number po, h.total_unit tUnit, h.total_amount tDollar, ' ||
' s.quantity qty, s.unit_price price,' ||
' (select (case when count(*) = 0 then ''Y'' else ''N'' end) ' ||
' from sewn.NT_edii_po_det_error ' ||
' where edi_det_sequ_id = d.edi_det_sequ_id ' ||
' ) eligible ' ||
' from sewn.nt_edii_purchase_size s, sewn.nt_edii_purchase_det d, ' ||
' sewn.nt_edii_purchase_hdr h, sewn.nt_edii_param_temp t ' ||
' where h.business_unit_id = t.business_unit_id ' ||
' and h.edi_sequence_id = t.edi_sequence_id ' ||
' and h.business_unit_id = d.business_unit_id ' ||
' and h.edi_sequence_id = d.edi_sequence_id ' ||
' and d.business_unit_id = s.business_unit_id ' ||
' and d.edi_sequence_id = s.edi_sequence_id ' ||
' and d.edi_det_sequ_id = s.edi_det_sequ_id ' ||
' ) group by bu, seq, po, tunit, tdollar, eligible ' ||
' ) ' ||
' group by bu, seq, po, tunit, tdollar, eligible)) ';
io_CURSOR := v_CURSOR;
END InvalidNOs;One remark why you should not use the assignment between ref cursor
variables.
(I remembered I saw already such thing in your code).
Technically you can do it but it does not make sense and it can confuse your results.
In the opposite to usual variables, when your assignment copies value
from one variable to another, cursor variables are pointers to the memory.
Because of this when you assign one cursor variable to another you just
duplicate memory pointers. You don't copy result sets. What you do for
one pointer is that you do for another and vice versa. They are the same.
I think the below example is self-explained:
SQL> /* usual variables */
SQL> declare
2 a number;
3 b number;
4 begin
5 a := 1;
6 b := a;
7 a := a + 1;
8 dbms_output.put_line('a = ' || a);
9 dbms_output.put_line('b = ' || b);
10 end;
11 /
a = 2
b = 1
PL/SQL procedure successfully completed.
SQL> /* cursor variables */
SQL> declare
2 a sys_refcursor;
3 b sys_refcursor;
4 begin
5 open a for select empno from emp;
6 b := a;
7 close b;
8
9 /* next action is impossible - cursor already closed */
10 /* a and b are the same ! */
11 close a;
12 end;
13 /
declare
ERROR at line 1:
ORA-01001: invalid cursor
ORA-06512: at line 11
SQL> declare
2 a sys_refcursor;
3 b sys_refcursor;
4 vempno emp.empno%type;
5
6 begin
7 open a for select empno from emp;
8 b := a;
9
10 /* Fetch first row from a */
11 fetch a into vempno;
12 dbms_output.put_line(vempno);
13
14 /* Fetch from b gives us SECOND row, not first -
15 a and b are the SAME */
16
17 fetch b into vempno;
18 dbms_output.put_line(vempno);
19
20
21 end;
22 /
7369
7499
PL/SQL procedure successfully completed.Rgds.
Message was edited by:
dnikiforov -
How to add cursor and for loop
PROCEDURE "TEST" is
bala number;
ins1 number;
ins2 number;
BEGIN
select sum(bal) into bala from (select sum(acp.acp_totbal) bal,acp_instruid from cs_strmap_t map,cs_instru_strips strip,cs_acpos_bkp acp
where c_int_instruid=c_srm_prncplinsid
and c_srm_prncplinsid=acp_instruid
and acp_acntnum!='SG030001'
group by acp_instruid
union
select sum(acp.acp_totbal) bal,acp_instruid from cs_strmap_t map,cs_instru_strips strip,cs_acpos_bkp acp
where c_int_instruid=c_srm_prncplinsid
and acp_acntnum!='SG030001'
and acp_instruid=c_srm_prntinsid
group by acp_instruid)view1;
dbms_output.put_line(bala);
select acp_instruid into ins1 from cs_strmap_t map,cs_instru_strips strip,cs_acpos_bkp acp
where c_int_instruid=c_srm_prncplinsid
and c_srm_prncplinsid=acp_instruid
and acp_acntnum='SG030001';
dbms_output.put_line('principal'||ins1);
select acp_instruid into ins2 from cs_strmap_t map,cs_instru_strips strip,cs_acpos_bkp acp
where c_int_instruid=c_srm_prncplinsid
and acp_acntnum='SG030001'
and acp_instruid=c_srm_prntinsid;
dbms_output.put_line('parent'||ins2);
update cs_acpos_bkp
set acp_totbal=-bala
where acp_instruid=ins2
and acp_acntnum='SG030001';
END;
i have written this code,i need to use cursor and for loops to get more than one rows and update also.
if there are more than 1 rows in cs_strmap_t,then the procedure throws an error stating that it cannot take 2 rows.
Edited by: 850836 on Apr 7, 2011 11:43 PMPROCEDURE "TEST" is
bala number;
ins1 number;
ins2 number;
CURSOR cur_1 IS
select sum(bal) bala from (select sum(acp.acp_totbal) bal,acp_instruid from cs_strmap_t map,cs_instru_strips strip,cs_acpos_bkp acp
where c_int_instruid=c_srm_prncplinsid
and c_srm_prncplinsid=acp_instruid
and acp_acntnum='SG030001'
group by acp_instruid
union
select sum(acp.acp_totbal) bal,acp_instruid from cs_strmap_t map,cs_instru_strips strip,cs_acpos_bkp acp
where c_int_instruid=c_srm_prncplinsid
and acp_acntnum='SG030001'
and acp_instruid=c_srm_prntinsid
group by acp_instruid)view1;
BEGIN
select acp_instruid into ins1 from cs_strmap_t map,cs_instru_strips strip,cs_acpos_bkp acp
where c_int_instruid=c_srm_prncplinsid
and c_srm_prncplinsid=acp_instruid
and acp_acntnum='SG030001';
dbms_output.put_line('principal'||ins1);
select acp_instruid into ins2 from cs_strmap_t map,cs_instru_strips strip,cs_acpos_bkp acp
where c_int_instruid=c_srm_prncplinsid
and acp_acntnum='SG030001'
and acp_instruid=c_srm_prntinsid;
dbms_output.put_line('parent'||ins2);
for var_for in cur_1
loop
update cs_acpos_bkp
set acp_totbal=var_for.bala
where acp_instruid=ins2
and acp_acntnum='SG030001'
and abs(acp_totbal)>abs(bala);
dbms_output.put_line(bala);
end loop;
END;
i wrote the following procedure,but the balance is not getting updated.
Getting this errors when there are more than 1 row in cs_strmap_t table
ORA-01422: exact fetch returns more than requested number of rows
ORA-06512: line 22
ORA-06512: at line 2 -
Hi..
I'm using a ref cursor query to fetch data for a report and works just fine. However i need to use dynamic sql in the query because the columns used in the where condition and for some calculations may change dynamically according to user input from the form that launches the report..
Ideally the query should look like this:
select
a,b,c
from table
where :x = something
and :y = something
and (abs(:x/:y........)
The user should be able to switch between :x and :y
Is there a way to embed dynamic sql in a ref cursor query in Reports 6i?
Reports 6i
Forms 6i
Windows 2000 PROHello Nicola,
You can parameterize your ref cursor by putting the query's select statement in a procedure/function (defined in your report, or in the database), and populating it based on arguments accepted by the procedure.
For example, the following procedure accepts a strongly typed ref cursor and populates it with emp table data based on the value of the 'mydept' input parameter:
Procedure emp_refcursor(emp_data IN OUT emp_rc, mydept number) as
Begin
-- Open emp_data for select all columns from emp where deptno = mydept;
Open emp_data for select * from emp where deptno = mydept;
End;
This procedure/function can then be called from the ref cursor query program unit defined in your report's data model, to return the filled ref cursor to Reports.
Thanks,
The Oracle Reports Team. -
How to pick max value from a column of a table using cursor and iteration
Hello Everybody
I have a table loan_detail
and a column in it loan_amount
now i want to pick values from this table using cursor and then by using iteration i want to pick max value from it using that cursor
here is my table
LOAN_AMOUNT
100
200
300
400
500
5600
700i was able to do it using simple loop concepts but when i was trying to do this by using cursor i was not able to do it .
Regards
PeeyushSQL> SELECT MAX(sal) Highest_Sal,MIN(sal) Lowest_Sal FROM emp;
HIGHEST_SAL LOWEST_SAL
5000 800
SQL> set serverout on
SQL> DECLARE
2 TYPE tmp_tbl IS TABLE OF NUMBER INDEX BY BINARY_INTEGER;
3 sal_tbl tmp_tbl;
4 CURSOR emp_sal IS
5 SELECT sal FROM emp;
6 counter INTEGER := 1;
7 BEGIN
8 FOR i IN emp_sal LOOP
9 sal_tbl(i.sal) := counter;
10 counter := counter + 1;
11 END LOOP;
12 DBMS_OUTPUT.put_line('Lowest SAL:' || sal_tbl.FIRST);
13 DBMS_OUTPUT.put_line('Highest SAL:' || sal_tbl.LAST);
14 END;
15 /
Lowest SAL:800
Highest SAL:5000
PL/SQL procedure successfully completed.
SQL> Even smaller
SQL> DECLARE
2 TYPE tmp_tbl IS TABLE OF NUMBER INDEX BY BINARY_INTEGER;
3 sal_tbl tmp_tbl;
4 CURSOR emp_sal IS
5 SELECT sal FROM emp;
6 counter INTEGER := 1;
7 BEGIN
8 FOR i IN emp_sal LOOP
9 sal_tbl(i.sal) := 1;
10 END LOOP;
11 DBMS_OUTPUT.put_line('Lowest SAL:' || sal_tbl.FIRST);
12 DBMS_OUTPUT.put_line('Highest SAL:' || sal_tbl.LAST);
13 END;
14 /
Lowest SAL:800
Highest SAL:5000
PL/SQL procedure successfully completed.
SQL> Edited by: Saubhik on Jan 5, 2011 4:41 PM -
I am having a problem accessing Hotmail email messages via Fireflox server. When I am in the Inbox, reviewing messages, it either freezes up or a "1 item" small icon window follows cursor and does not allow me to enter messages or do anything. Have to log off and start over. Suggestions>?
Can you detect any pattern to it, whether related to messages with attachments, or particular advertising on the page, etc.?
When you have a problem with one particular site, a good "first thing to try" is clearing your Firefox cache and deleting your saved cookies for the site.
1. Clear Firefox's Cache
orange Firefox button ''or'' Tools menu > Options > Advanced
On the Network mini-tab > Offline Storage : "Clear Now"
2. If needed, delete the site's cookies here
While viewing a page on the site, right-click and choose View Page Info > Security > "View Cookies"
(Usually the dialog will refer to live.com rather than hotmail.com, that's normal.)
Then try reloading the page and logging in again. Does that help? -
Multi coloured spinning cursor and mac air keeps freezing?
multi coloured spinning cursor and mac air keeps freezing?
Force Quit .
Press command + option + esc keys together at the same time for 3 seconds. Wait.
When Force Quit window appears, select the application if not already.
Press Force Quit button at the bottom of the window. Wait.
Application will quit.
http://support.apple.com/kb/HT3411
Start up in Safe Mode.
http://support.apple.com/kb/PH11212?viewlocale=en_US
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