Equivalent of select distinct
Hi all,
I have a dataset brought into my Flex app by a server-side database call as XML. I then need to use this same dataset in a couple of different places, eg in a grid, as chart data, in a combo etc. So far no problem.
Now, for the combo entries what I would like to do is the equivalent of SQL "select distinct field_name from table_name", but applied directly to the XML I have brought back already. Is there such a beast in the XML-handling methods? I have found a work-around which sets up an Array, then cycles round the XML nodes and either adds the relevant field value as the next entry or skips it accordingly. But this seems unduly manual and (I suspect) will not be very snappy as the data set grows. Just now I am working with a fairly small test set but that will change.
Any suggestions?
Thanks in advance,
Richard
You're welcome I think that so far there isn't a method like that
probably an enhance request. In that case you'll need to traverse the
XML and add the items to another XMLList or an AC.
Sincerely,
Michael
El 27/04/2009, a las 8:51, Richard_Abbott <[email protected]> escribió:
>
Thanks Michael and Barna, but this doesn't really address the
problem. The data is well structured and I am using E4X methods. But
the examples don't (I think) meet the need. Take the trilemetry
example. In the XML file we have two individuals named "John". The
requirement is to come up with a reduced list of unique elements so
including Bob, John, Jane, Art, Brad... ie John only the once as we
already have that name in. Clearly in this case not much of a
reduction but where I am generating a selection box where the
categorisation is much more common it is essential. Take Fisher's
Iris data - you have 150 rows consisting of 50 each of three kinds
of iris. Obviously in the drop-down selector you just want 3 names
not 150. I think it would be much neater if I could just pull them
out with an E4X-style query, but so far I haven't found a method for
this, hence the work-around of manually looping and testing.
Richard
>
Similar Messages
-
Problems with "Select Distinct" Statement
Hi... I've a little problem with my SQL Statement...
I've a Table in a DataBase with Solds of the Month... the fields are: vta_fecha, vta_prod, vta_total, vta_mesa.
I've to Select only the distincts fields of vta_prod... selected by vta_fecha and vta_mesa...
My code is like this: try{
Class.forName("sun.jdbc.odbc.JdbcOdbcDriver");
conec = DriverManager.getConnection("jdbc:odbc:Driver={Microsoft Access Driver (*.mdb)};DBQ=C:/POOL/Data/BaseDat.MDB");
state = conec.createStatement(ResultSet.TYPE_SCROLL_SENSITIVE,ResultSet.CONCUR_READ_ONLY);try{
rec = state.executeQuery("Select DISTINCT vta_prod, vta_fecha, vta_mesa from Ventas where vta_fecha = #" + Fecha_q + "# And vta_mesa = 0");
rec.first();
int x = 0;
while (rec.isAfterLast()==false){
x++;
rec.next();
rec.first();
if (x > 0){
Productos = new String[x];
Total_Vta = new int[x];
Cant_Prod = new int[x];
x = 0;
while (rec.isAfterLast() == false){
Productos[x] = rec.getString("vta_prod");
rec.next();
x++;
else{
Productos = new String[0];
Total_Vta = new int[0];
Cant_Prod = new int[0];
}catch(Exception e){JOptionPane.showMessageDialog(null,e.getMessage());}Now, in the Table I have only 3 diferents vta_prod, but this Statement returns 9 Rows... and I don't know why...
Please help me...
Regards...I don�t have a complete picture because I don�t know what values you are passing in the select and I don�t know your column types but this is what I think is happening from what you have shared.
You may have misunderstood what the DISTINCT keyword does.
The DISTINCT keyword applies to the full set of columns in the select (not just the first column). So in your case it would be equivalent to:
SELECT vta_prod, vta_fecha, vta_mesa
FROM Ventas
WHERE ...
GROUP BY by vta_prod, vta_fecha, vta_mesa
So, it doesn't matter that you only have 3 distinct vta_prod values if you have multiple values being returned in the other columns. The vta_mesa column can only a return a single value as �0�. That leaves the vta_fecha column which is probably a date/time column and is probably the column that is returning the three other distinct values (one date with three distinct times).
(3 vta_prod) x (3 vta_fecha) x (1 vta_mesa) or 3x3x1 = 9 rows
So find a way to strip the time from vta_fecha in your select statement and your SQL should return the results you expect. I�m not an Access expect but I think I remember you can use something like the �Convert� or �DatePart� functions to make that happen (check your documentation to be sure)..
A couple of asides;
1) You should use a PreparedStatement and rarely if ever use Statement.
2) You should start Java variable names with lower case. -
Select distinct records without using distinct
hi experts,
my retrieved data like these:
cnt_id cnt_type rcrd_id wrkflw_id
558848 PRODUCT 553503 248
558848 PRODUCT 553503 248
558848 PRODUCT 553503 248
558808 PRODUCT 553463 248
558808 PRODUCT 553463 248
558808 PRODUCT 553463 248
558810 PRODUCT 553463 248
558810 PRODUCT 553463 248
558810 PRODUCT 553463 248
now i want to select one record for each cnt_id without using any distinct function .. how can i do that?
regards,
SKPyou can use the below query
select * from t where rowid in (select max(rowid)
from t group by cnt_id)You're query is not the equivalent of DISTINCT.
SQL> ed
Wrote file afiedt.buf
1 create table t as
2 (select 558848 as cnt_id, 'PRODUCT' as cnt_type, 553503 as rcrd_id, 248 as wrkflw_id from dual union all
3 select 558848, 'RETURN', 553503, 248 from dual union all
4 select 558848, 'PRODUCT', 553503, 248 from dual union all
5 select 558808, 'PRODUCT', 553463, 248 from dual union all
6 select 558808, 'PRODUCT', 553463, 248 from dual union all
7 select 558808, 'PRODUCT', 553463, 248 from dual union all
8 select 558810, 'PRODUCT', 553463, 248 from dual union all
9 select 558810, 'PRODUCT', 553463, 248 from dual union all
10* select 558810, 'PRODUCT', 553463, 248 from dual)
11 /
Table created.
Elapsed: 00:00:00.01
SQL> select * from t where rowid in (select max(rowid) from t group by cnt_id);
CNT_ID CNT_TYP RCRD_ID WRKFLW_ID
558810 PRODUCT 553463 248
558808 PRODUCT 553463 248
558848 PRODUCT 553503 248
Elapsed: 00:00:00.00
SQL> select distinct * from t;
CNT_ID CNT_TYP RCRD_ID WRKFLW_ID
558810 PRODUCT 553463 248
558808 PRODUCT 553463 248
558848 RETURN 553503 248
558848 PRODUCT 553503 248
Elapsed: 00:00:00.00
SQL> -
Query help in select Distinct on one column.
CREATE GLOBAL TEMPORARY TABLE Table1 (
ID1 varchar2(100) ,
Name1 varchar2(100),
Name11 varchar2(100)
insert into Table1 values ('a','n1','h3');
insert into Table1 values('b','n2','h2');
insert into Table1 values('a','n3','h1');
insert into Table1 values('c','n4','h5');
insert into Table1 values ('c','n5','h4');
insert into Table1 values('d','n6','h6');
select * from Table1;
ID1,NAME1, NAME11
a, n1, h3
b, n2, h2
a, n3, h1
c, n4, h5
c, n5, h4
d, n6, h6
I am trying to select distinct ID1 and all values associated with it which is max row.I want to result as -
ID1,NAME1, NAME11
a, n3, h1
b, n2, h2
c, n5, h4
d, n6, h6
Can you please help me to write simple query to get above result.
Edited by: 871447 on Jul 25, 2011 9:42 AM
Edited by: 871447 on Jul 25, 2011 9:45 AMHi,
Do a self-join, to combine the two rows for each value of id1 onto one output row.
Make it an outer join, in case there is only one row with a vlaue for id1.
SELECT l.id1
, l.name1
, NVL ( r.name11
, l.name11
) AS name11
FROM table1 l
LEFT OUTER JOIN table1 r ON l.id1 = r.id1
AND l.name1 < r.name1
;Edited by: Frank Kulash on Jul 25, 2011 12:57 PM
Sorry, I mis-read the problem.
Lee's solution, above, assumes that name1 is unique, as it is in your sample data.
What output would you want if that's not the case?
If name1 is not unique, but the combination of (id1, name1) is unique, then you can modify Lee's solution like this:
SELECT *
FROM table1
WHERE (id1, name1) IN (
SELECT id1
, MAX (name1)
FROM table1
GROUP BY id1
;Or, if you can't make any assumptions about uniqueness, you might need something like this:
WITH got_r_num AS
SELECT id1, name1, name11
, ROW_NUMBER () OVER ( PARTITION BY id1
ORDER BY name1 DESC
, name11 DESC
) AS r_num
FROM table1
SELECT id1, name1, name11
FROM got_r_num
WHERE r_num = 1
; -
How to select distinct values from a table when it has composite primary ke
Hi
I have the requirement like , I need to select distinct one column values from the table which has composite primary key. How to acheive this functioinality using view object.
Eg : Table 1 has col1 and col2, col3
col1 col2 col3
1 A NA
1 B NA
2 A NA
3 C NA
2 D NA
primary key (col1,col2)
I have to select distinct col1.
ThanksHi
I got the solution for above. By Creating the read only view object we can acheive this.
thanks -
Need of SQL query in selecting distinct values from two tables
hi,
I need a query for selecting distinct values from two tables with one condition.
for eg:
there are two tables a & b.
in table a there are values like age,sex,name,empno and in table b valuses are such as age,salary,DOJ,empno.
here what i need is with the help of empno as unique field,i need to select distinct values from two tables (ie) except age.
can anybody please help me.
Thanks in advance,
RatheeshNot sure what you mean either, but perhaps this will start a dialog:
SELECT DISTINCT a.empno,
a.name,
a.sex,
b.salary,
b.doj
FROM a,
b
WHERE a.empno = b.empno;Greg -
Serious performance problem - SELECT DISTINCT x.JDOCLASSX FROM x
I am noticing a huge performance problem when trying to access a member that
is lazily loaded:
MonitorStatus previousStatus = m.getStatus();
This causes the following query to be executed:
SELECT DISTINCT MONITORSTATUSX.JDOCLASSX FROM MONITORSTATUSX
This table has 3 million records and this SQL statement takes 3 minutes to
execute! Even worse, my app heavily uses threads, so this statement is
executed in each of the 32 threads. As a result the application stops.
Is there any way that I can optimize this? And more importantly, can Kodo
handle a multithreaded app like this with a huge database? I've been having
a lot of performance problems since I've started doing stress & load
testing, and I'm thinking Kodo isn't ready for this type of application.
Thanks,
MichaelYou can prevent this from happening by explicitly enumerating the valid
persistent types in a property. See
http://docs.solarmetric.com/manual.html#com.solarmetric.kodo.PersistentTypes
for details.
>
Inconveniently, this nugget of performance info is not listed in the
optimization guide. I'll add in an entry for it.This setting did in fact prevent the query from running which fixed the
problem. It definitely belongs in the optimization guide.
And more importantly, can Kodo
handle a multithreaded app like this with a huge database? I've beenhaving
a lot of performance problems since I've started doing stress & load
testing, and I'm thinking Kodo isn't ready for this type of application.I'd like to find out more information about details about your issues. We
do a decent amount of stress / load testing internally, but there are
always use cases that we don't test. Please send me an email (I'm assuming
that [email protected] is not really your address) and let's
figure out some way to do an analysis of what you're seeing.This email is just for posting to usenet, to avoid spam. I'm now running my
app through stress/load testing so I hope to discover any remaining issues
before going into production. As of this morning the system seems to be
performing quite well. Now the biggest performance problem for me is the
lack of what I think is called "outer join". I know you'll have this in 3.0
but I'm suprised you don't have this already because not having it really
affects performance. I already had to code one query by hand with JDBC due
to this. It was taking 15+ minutes with Kodo and with my JDBC version it
only takes a few seconds. There are lots of anti-JDO people and performance
issues like this really give them ammunition. Overall I just have the
impression that Kodo hasn't been used on many really large scale projects
with databases that have millions of records.
Thanks for configuration fix,
Michael -
Issue with "Select Distinct" query in Oracle 10g against Oracle 9i
Hi,
I would appreciate if some one help me here because it is really urgent.
We are upgrading our database from 9i to 10g.
There are the "Select distinct" queries in the code which populated the grid on the applications screens. We found a difference in 9i and 10g the way the result is populated for these queries. If "Select Distinct" query wihtout a order by clause is executed in 9i then the result is automatically sorted. But Oracle 10g does not do this.
We can change the queries adding order by clause but we are almost at the end of the testing and want to know if there is any way that we can do this from database settings. Would there be any impact of these settings change on overall operation of Oracle 10g?
I would appreciate if some one can help me here.
Thanks,
Dineshthen the result is automatically sorted.No. Oracle may have done a sort operation to perform the distinct, but it still did not guarantee the order of your results.
In 10g and in 9i, if you want your results in a certain order you must use order by. -
Select Distinct and join in ODI
Hi,
I have following task to perform: I am loading metadata into Planning dimension from Oracle database. I have two tables
1. "Sales"
Columns: Name, Number, Value
Sample Data:
Product 1, 10, 200
Product 2, 30, 100,
Product 1, 15, 500
2. P&R
Columns:
Name, Alias
Product 1, SampleSoda1
Product 2, SampleSoda2,
Resource 1, CanForSoda,
Resource 2, CO2
What I need to do is: I have to select name and alias from second table of all products that were sold.
So I need to select distinct Name from Table 1, naxt join it with Table 2 (so I have Name and Alias) and load it to planning.
I am a little confused how to do it.
Any help would be great!
Best regards,
GregHi Greg,
What you can do is either :
- Create a yellow interface with your table Sales as source. Map the name column directly in the target. In the flow tab, click on your target and select "Distinct rows".
- Create a second interface, with your first interface as source. Select the "Use Temporary Interface as Derived Table (Sub-Select)" checkbox.
- Add your second datastore and join it. Or you can use a lookup table.
OR
- Create an interface with Sales and P&R as source (or set P&R as a lookup table).
- Go on the flow tab and select "Distinct rows".
If you've a lot a data in the first table, I would go for the first solution.
Hope it helps.
Regards,
JeromeFr
Edited by: JeromeFr on Feb 14, 2013 9:52 AM
To be more clear in the first step of solution 1 -
Select distinct for a date column in present. service when creating prompt
hi all
I am trying to create some new prompts in my answers and I have the following problem. When I try to create a new prompt on a date column ( for example Modification Date), when I try to run this report on this prompt it is displaying the same date a lot of times ( for example 2/4/11 it is being displayed 4 times).
Is there any way i can change this, so to display distinct dates?
Thank you and best regardsHi Deva
I am trying to use this, but in the system are being saved the date + hour.
When i try select distinct modification date from My_view, i still have the same dates because they have different hours.
When i try select disctinct to_date(modification_date)..... I am having an error in BI.
Please help me to solve this issue.
Regards -
Select Distinct (More than one column)
Hi All,
I have the following SQL statement written in MySQL that returns only one row per MODCODE with the associated DEPTCODE of AE:
SELECT DISTINCT
EL_MODULE.DEPTCODE, EL_MODULE.MODCODE, EL_MODULE.MODNAME, EL_MODULE.MODLEVEL, EL_DEPTLEVEL.DEPTLEVELHEADER
FROM EL_DEPTLEVEL, EL_MODULE
WHERE EL_MODULE.MODLEVEL = EL_DEPTLEVEL.LEVELCODE AND EL_MODULE.DEPTCODE='AE' ORDER BY EL_MODULE.MODLEVEL
However when I attempt to use this in oracle it returns three rows, could somebody point out what it is I need to change to get this working correctly in oracle.
Hope someone can help.
JonDuplicates? No way! This query returns unique comibination of
EL_MODULE.DEPTCODE,
EL_MODULE.MODCODE,
EL_MODULE.MODNAME,
EL_MODULE.MODLEVEL and
EL_DEPTLEVEL.DEPTLEVELHEADER
Cheers
Sarma. -
When using ‘insert into table2 select distinct field from table1′ and table2 contains a field with a default value sys_guid(), the distinct operator does not seem to work ! This was tested on Oracle 10.2.0.4 on 64 bit linux. See the following SQL code to prove it :
create table table1 (field1 varchar2(100));
insert into table1 (field1) values (‘value1′);
insert into table1 (field1) values (‘value1′);
insert into table1 (field1) values (‘value2′);
– distinct and to_char(sysdate) function gives the correct 2 rows (‘value1′ and ‘value2′)
create table table2 (field1 varchar2(100), field2 raw(16) default to_char(sysdate, ‘hh’));
insert into table2(field1) select distinct field1 from table1;
select * from table2;
rollback;
drop table table2 purge;
– distinct and sys_guid function gives 3 rows (twice ‘value1′ !!) instead of 2
create table table2 (field1 varchar2(100), field2 raw(16) default sys_guid());
insert into table2(field1) select distinct field1 from table1;
select * from table2;
rollback;
drop table table2 purge;
– with group by : no problem
create table table2 (field1 varchar2(100), field2 raw(16) default sys_guid());
insert into table2(field1) select field1 from table1 group by field1;
select * from table2;
rollback;
drop table table2 purge;
drop table table1 purge;It looks like I can reproduce (on XE 10.2.0.1), with or without using a default for sys_guid:
SQL> select banner from v$version where rownum=1;
BANNER
Oracle Database 10g Express Edition Release 10.2.0.1.0 - Product
1 row selected.
SQL> create table table1 (field1 varchar2(100));
Table created.
SQL> insert into table1 (field1) values ('value1');
1 row created.
SQL> insert into table1 (field1) values ('value1');
1 row created.
SQL> insert into table1 (field1) values ('value2');
1 row created.
SQL> -- distinct and to_char(sysdate) function gives the correct 2 rows (‘value1' and ‘value2')
SQL> create table table2 (field1 varchar2(100), field2 raw(16) default to_char(sysdate, 'hh'));
Table created.
SQL> insert into table2(field1) select distinct field1 from table1;
2 rows created.
SQL> select * from table2;
FIELD1 FIELD2
value1 11
value2 11
2 rows selected.
SQL> drop table table2 purge;
Table dropped.
SQL> -- distinct and sys_guid function gives 3 rows (twice ‘value1' !!) instead of 2
SQL> create table table2 (field1 varchar2(100), field2 raw(16) default sys_guid());
Table created.
SQL> insert into table2(field1) select distinct field1 from table1;
3 rows created.
SQL> select * from table2;
FIELD1 FIELD2
value1 5AF743C0FD484D578E84276C875C5BC1
value1 725ABE6066BF42E2A78406BD549D9E85
value2 CC43E3C688AF428B885A0F4EA24482CB
3 rows selected.
SQL> drop table table2 purge;
Table dropped.
SQL> -- without using DEFAULT, here Max is right (see posts below)
SQL> create table table2 (field1 varchar2(100), field2 raw(16));
Table created.
SQL> insert into table2(field1, field2) select distinct field1, sys_guid() from table1;
3 rows created.
SQL> select * from table2;
FIELD1 FIELD2
value1 7B277A2068AF468EBC06E33F6700B9E3
value1 9644C1C8A909489F98B51531BDD282D9
value2 8707FD2E6AB94EA7810D8D4AB19AB091
3 rows selected.
SQL> drop table table2 purge;
Table dropped.
SQL> -- with group by : no problem
SQL> create table table2 (field1 varchar2(100), field2 raw(16) default sys_guid());
Table created.
SQL> insert into table2(field1) select field1 from table1 group by field1;
2 rows created.
SQL> select * from table2;
FIELD1 FIELD2
value2 202A87C86EF446D8915B3C976385D68F
value1 484625A675524FA09CC393A78411B38A
2 rows selected.
SQL> drop table table2 purge;
Table dropped.
SQL> drop table table1 purge;
Table dropped.Edited by: hoek on Feb 18, 2010 11:29 AM -
Ora-00600 error on select distinct when using cursors
Hi, we are using oracle9iFS version 9.0.1.1.0. When I execute the following query in sqlPlus an ora-00600 error occurs.
Here is the query:
SELECT DISTINCT ODMV_FOLDER.NAME,
CURSOR(SELECT ODMV_DOCUMENT.NAME
FROM ODMV_DOCUMENT
WHERE ODMV_DOCUMENT.ID = ODMV_FOLDERRELATIONSHIP.RIGHTOBJECT)as Document
FROM ODMV_FOLDER,
ODMV_FOLDERRELATIONSHIP
WHERE ODMV_FOLDER.CREATOR = 96 /*this is the user 'system'*/
AND (ODMV_FOLDER.ID = ODMV_FOLDERRELATIONSHIP.LEFTOBJECT)
I have no clue why is this happening. I might be doing something wrong since a similar query with a nested cursor works with the scott/tiger schema. Your help is greatly appreciated. Thank you in advance.
Alfonso.I was able to reproduce this error. This looks like a bug in the RDBMS; I would suggest posting on their newsgroup or working with support to handle this problem.
-
Select distinct is using the wrong index
Hello,
I have an indexes question?
I have a table with 1M rows, the table structure is as follows:
create table X(aTime DATE , a1 NUMBER(28,0), a2 NUMBER(28,0), a3 NUMBER(28,0), .... , a20 NUMBER(28,0) );
I have also 2 indexes:
- IDX1 is defined on (aTime, a1, a2, a3).
- IDX2 is defined on (a1, a2, a3).
I run the following query: "SELECT DISTINCT A1, A2, A3 from X;" and see that the optimizer chooses to do a FTS (full table scan) though I was expecting him to use IDX2 because it looks like a "covering" indexes giving all the answers to the query without fetching data rows.
When I try to force him to use indexes, using the following hint "/*+INDEX(X IDX2)*/" the optimizer chooses IDX1.
When I use same hint after I dropped IDX1 the optimizer still prefers to make FTS .
Some general info:
- a1, a2 and a3 have about 500 distinct values each).
- db version 8.1.7.4.
- all tables and indexes are analyzed.
I have two questions:
===============
1.
Why does the optimizer prefers IDX1 (aTime, a1, a2, a3) over IDX2 (a1, a2, a3) when the query specifically requests distinct values of (aTime, a1, a2, a3), isn't there a shortcut the optimizer should use here?
2.
When I request the optimizer to use specific index (using hints), shouldn't it use the index I request regardless of his calculations? If not, is there any way to change this behavior?
Tal Olier
[email protected]You said you analyzed the tables and indexes. Did you also analyze the indexed columns?
A full table scan may be a better execution plan than using an index, especially if you are selecting the full table.
Remember that a hint is jut that, a hint. It suggests to the optimizer to do something, but the optimizer may still choose a different plan. -
Something´s going wrong with select distinct (Oracle 10g)
Our database is oracle 10g release 2 and the query statement is:
select distinct last_name
from students;
and the query returns all of the last_names without an specific order..
If I execute the same query in oracle 9i the query returns all of the last_name in alphabetic order.
Why is it different on Oracle 10g?See also this blog entry from Mr. Kyte.
C.
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