Using rownum in EJB-QL ..Pagination using CMP 2.1

Hi ,
Hope this is the right forum .. rather than JDBC .
My requirement is to implement Pagination using EJB2.1 on weblogic with Oracle DB. This is for an application which is quite old system and is not ready yet to be migrated to EJB3.0. So we are struck with EJB2.1 at the moment.
We are using EJB-QL to get Search result and now need to add Pagination logic in it. I can find weblogic.ejb.PreparedQuery.setMaxElements() API to specify the upper limit but what am looking for is a lower limit ..somthing like setFirstRow() ..
Can it be done using CMP Entity Bean 2.1 .. EJBQL or someother way ?
I have the sql for pagination but am not sucessful in translating it to EJB-QL
select * from
select /*+ FIRST_ROWS(n) */ a.*, ROWNUM rnum from
(your_query_goes_here) a
where ROWNUM <=:MAX_ROW_TO_FETCH
where rnum >= :MIN_ROW_TO_FETCH;
Thanks in advance ! I hope I get a solution soon ..
Edited to get some answers !!!
is it possible to use rownum in EJBQL ? I know rownum is specific to Oracle and my application will stay with Oracle. I get this exception
"EJB QL compilation encountered error: [EJB:013042]The Identifier 'rownum' is neither a cmp-field nor a cmr-field. Re-examine your query."
Edited by: user11305835 on Oct 12, 2009 10:48 PM

Beevin
Both two are not even validated,
but with the first one as select max(c.id) from customer as c , in this case it is validated but while deploying it is error as , object must be return
But when i saw the ejb2.1 specification we can write this type of queries also ?
Is it problem with was any thing
Regards
Somaraju

Similar Messages

I am using webservice in ejb but it is giving Naming exception in NetWeaver

hai
this Guru.
i am working as javadeveloper .
in my project i am using webservices in ejbs.
i am using netweaverdeveloper .
my problem is whlie accessing webservices in ejbs it is giving Namingexception .
please tell me the procedure for accesing WEBSERVICES IN EJB BY USING NETWEAVER DEVELOPER STUDIO.
                          THANQQQQQ
                   GURU FROM MOBILEONE PTV LIMITED
                          HYDERABAD
                          INDIA

Hi Guru,
Refer these links
Accessing the Web Services Context from a WS-EJB ->
http://help.sap.com/saphelp_webas630/helpdata/en/a6/835f3e1e7d7937e10000000a114084/content.htm
Accessing the web service from webdynpro ->
https://www.sdn.sap.com/irj/servlet/prt/portal/prtroot/docs/library/uuid/9fc0e990-0201-0010-199c-e38fc6dafb5d
Regards,
Uma

Issue While executing the Query for Pagination using ROWNUM with like

Issue While executing the Query for Pagination using ROWNUM with like.
Database is Oracle11G.
Oracle Database Table contains 8-9 lakh records
1) SQL equal (=)
SELECT /*+ FIRST_ROWS(n) */ ROWNUM RNUM, A.* FROM LINE A
WHERE A.REFERENCE = 'KMF22600920'
Execution Time:- 0.00869245 seconds
Returns 2 resultsets
2) SQL like (one %)
SELECT /*+ FIRST_ROWS(n) */ ROWNUM RNUM, A.* FROM LINE A
WHERE A.REFERENCE = 'KMF22600920%'
Execution Time:- 0.01094301 seconds
Returns 2 resultsets
3) SQL like (two%)
SELECT /*+ FIRST_ROWS(n) */ ROWNUM RNUM, A.* FROM LINE A
WHERE A.REFERENCE like '%KMF22600920%'
Execution Time:- 6.43989658 seconds
Returns 2 resultsets
In Pagination, we are using Modified version of SQL Query 3) with ROWNUM as mentioned below :-
4) SELECT * FROM (
SELECT /*+ FIRST_ROWS(n) */ ROWNUM RNUM, A.* FROM LINE A
WHERE REFERENCE like '%KMF22600920%' AND ROWNUM <= 20 ) WHERE RNUM > 0
Execution Time:- Infinite
ResultSets:- No as execution time is infinite
a) Instead of like if we use = in the above query it is returning the 2 resultsets (execution time 0.02699282 seconds)
b) Instead of two % in the above query, if use one example REFERENCE like 'KMF22600920%' it is returning the 2 resultsets (execution time 0.03313019 seconds)
Issue:- When using two % in like in the above query i.e. REFERENCE like '%KMF22600920%' AND ROWNUM <= 20 ) , it is going to infinite.
Could you please let us know what is the issue with two % used in like and rownum
5) Modified version of Option1 query (move out the RNUM condition AND RNUM <= 20)
SELECT * FROM (
SELECT /*+ FIRST_ROWS(n) */ ROWNUM RNUM, A.* FROM LINE A
WHERE REFERENCE like '%KMF22600920%' ) WHERE RNUM > 0 AND RNUM <= 20
Execution Time:- 7.41368914 seconds
Returns 2 resultsets
Is the above query is best optimized query which should be used for the Pagination or still can improve on this ?

This would be easier to diagnose if there was an explain plan posted for the 'good' and 'bad' queries. Generally speaking using '%' on both sides precludes the use of any indexes.

Restricting number of rows in EJB QL using rowNum or rowId

Hii Javaites
I am using EJB finder methods to get a a list of records from database.
Now i want that only particular number of records should be fetched.
For tht i want 2 use rownum or rowId.
Can anyone plz tell me can we do tht in EJB QL.
I m using Weblogic 8

shouldn't use rownum or rowid to do such a thing.
%

How to use auto incremented tabe to create a CMP Entity Bean

hi,
I want create a CMP entitybean with an auto incremented table in
Oracel. So I need to know
- how to create a table with an auto-incremented field in oracel and
- how to change the create() method according to that.
I am using Sun studio enterprise for EJB developing.
kaushalya

For auto increment in Oracle you should use Sequence/Trigger combination.
And useful thread from EJB forum:
http://forum.java.sun.com/thread.jspa?forumID=13&threadID=478783

How Oracle returns queries & using rownum

Hi, I need to limit query results using rownum, but my question is regarding how Oracle retrieves its data.
Assume I have a table containing 500 records and my query without using rownum will retrieve 62 of those records. The actual query will use rownum and limit results to 20.
I have a JSP that will display those first 20. It has a simple feature for pagination, a "next" button that will retrieve the next results. So far simple enough, going forwards is easy. But how about going back.
I am trying to work out the SQL for using a "previous" button, so for example, say records 40-60 are being displayed, and say the first record on that page has a primary key value of 200, what should the SQL be to retrieve the previous 20 records using rownum ? I ask because if I do:
select * from tablename where pri_key < 200 and rownum <=20;
I know it will retrieve 20 records, but would the query fetch its results from the beginning of the table or would it count backwards from 200 ? If it is the first way, how could I word the SQL query to go backwards from 200 ? I am pretty sure it will start from the beginning and thats what I don't want. I know there are pagination tags for jsp out there but I want to do this myself.
Thanks
Kevin
Message was edited by:
MrVen

First, you need to understand that rownum is only assigned when a record is selected for output, it has nothing to do with any sort of internal order of the table (like insertion order). The same row can have a different rownum even for two invocations of the same query on the same data if the optimizer chooses a different access path. The only way to get a repeatable set of rownum is to sort the records by some field.
Second, any SQL statement you issue will be executed essentially in isolation. Oracle has no idea what query you executed previously. So, your query:
SELECT *
FROM tablename
WHERE pri_key < 200 and
      rownum <=20;will select a random set of 20 rows wih a primary key less than 200. It is likely to be the first (i.e. lowest values of the pk) rows, but that is not guaranteed.
The cannonical way to paginate rows is something like:
SELECT col1, col2, ...
FROM (SELECT col1, col2, ..., rownum rn
      FROM (SELECT col1, col2, ...
            FROM table
            WHERE <conditions>
            ORDER BY pk) ti
      WHERE rownum <= :maxrownum) to
WHERE rn >= :minrownumThe innermost query (with the <condition>) selects the appropriate rows and sorts them, in this case by the pk.
The middle query (rownum <- :maxrownum) discards the rows that would be after the last record you want to display. By using the maxrownum here, it gives Oracle information that allows it to do a fast sort on the inner query if possible.
In a fast sort, Oracle will get the first maxrownum rows from the query and sort them, then when it gets the next row, it checks if it is less than the highest value already found. If it is, it slots it into the correct place and discards the highest value, otherwise it discards that row.
The outermost query simply discards the records where the row number after sorting is less than the minimum value.
Another alternative may be:
SELECT col1, col2, ...
FROM (SELECT col1, col2, ...,
             ROW_NUMBER() OVER(ORDER BY pk) rn
      FROM table
      WHERE <conditions>)
WHERE rn BETWEEN :minrownum AND :maxrownumdepending on your database version, and your actual query.
Note tha pagination like this is expensive.
HTH
John
The outermost

Pagination using table growing property and multi-select table issues

Hi,
We're using the growing property on a table, thus the pagination is handled by the control it self.
However, if we want to update some item in the table, in order to get those details reflected, we're refreshing the model, which is performance intensive.
Is there any way we can update the UI only without creating any UI inconsistencies?
Another question is that, is there any way to disbale the checkbox on the table items, based on some property from the backend. we tried to use editable property, but it hides the entire row.
We need to disable the checkbox on the rows for particular items?
Also, I need to know any resources on the mobile library where I can find the CSS related documentaion.
Like we need to create a icon + text structure, which controls should be ideal to use? I have used
<HBox><Icon src="abc"/><Text text="abc"/></Hbox>, but it creates alignment issues. Any ideas here?
Thanks!
Aamir

855354 wrote:
We are implementing pagination in our application and comparing the scrollable result set approach with using ROWNUM provided by oracle.The rownum approach scales better.
Does this literrally mean that Oracle stores all the records in client-side memory cache? Well if it is scrollable it has to store all the rows somewhere, that is the disadvantage.
Can we use fetchSize attribute or any other work around to limit the number of records in client-side memory?No. If you want that behavior that is how the rownum approach works.
In the above case, when MAX_ROW_TO_FETCH is a large number (say 50000), then oracle will have to create a temporary table in memory with all the 50000 records and then will fetch from that table required records as per MIN_ROW_TO_FETCH.No, that is not how it works, where did you read that?
In this case, reading rest of the records and storing in temporary in memory table will impact performance. Is my understanding correct or i am missing something here?Your understanding is not correct. The rownum approach does not work the way you think and behaves more like the way you want the scrollable result set to work.

Insert data into table from JSP page using Entity Beans(EJB 3.0)

I want to insert data into a database table from JSP page using Entity Beans(EJB 3.0).
1. I have a table 'FRIENDS', (in Oracle 10g database).
2. It has two columns, 'NAME' and 'CITY'. Both have datatype strings(varchar2).
3. Now from a JSP page, having two textfields, 'NAME' and 'CITY', I want to insert data into table 'FRIENDS'.
4. In between JSP and database is a Entity Bean(EJB 3.0) and a stateless session bean.
5. I am using JDev as editor.
Please provide me code ASAP or link with similar example.
Thank you.
Anurag

Hi,
I am also trying that scenario. So u can
Post the jsp form data to a Servlet which will act as a Controller.
In the servlet invoke the business method.
Similar kind of app is in www.roseindia.net
Hope this would help u.
Meanwhile if u get any optimal solution, pls post it.
Thanks,
Happy Java Coding.

Issue with complete refresh on materialized view when using rownum

Hi all,
I had an issue with rownum when using complete refresh
I am using rownum when creating materialized view and it is generation correctly.But the issue was when i am refreshing the same ,rownum was not getting sorted in ascending order.
anyone had come across this scenario

rownum is determined as the row is output, so "order by rownum" does literally nothing.
http://docs.oracle.com/cd/B19306_01/server.102/b14200/pseudocolumns009.htm

Select a range of rows to be displayed using ROWNUM

I am trying to select a range of records to be displayed using Rownum
It works using MINUS
SQL> select rownum,department_id,department_name from departments where rownum <= 20
minus
select rownum,department_id,department_name from departments where rownum < 11;
but does not work if a range is specified
select rownum,department_id,department_name from departments where rownum >= 11 and rownum <= 20;
What has gone wrong?
Details of what I have tried are as follows:
Connect to the sample schema HR
SQL> connect hr/hr
SQL> desc departments
Name Null? Type
DEPARTMENT_ID NOT NULL NUMBER(4)
DEPARTMENT_NAME NOT NULL VARCHAR2(30)
MANAGER_ID NUMBER(6)
LOCATION_ID NUMBER(4)
List all records in Departments
SQL> select rownum,department_id,department_name from departments;
ROWNUM DEPARTMENT_ID DEPARTMENT_NAME
1 10 Administration
2 20 Marketing
3 30 Purchasing
4 40 Human Resources
etc......
26 260 Recruiting
27 270 Payroll
27 rows selected.
List the first 10 records in DEPARTMENTS
SQL> select rownum,department_id,department_name from departments where rownum <= 10;
ROWNUM DEPARTMENT_ID DEPARTMENT_NAME
1 10 Administration
2 20 Marketing
etc.....
10 100 Finance
List row number from 11 to 20, but cannot no rows selected. Why?
SQL> select rownum,department_id,department_name from departments where rownum >= 11 and rownum <= 20;
no rows selected
Use of MINUS can retrieve row number from 11 to 20
SQL> select rownum,department_id,department_name from departments where rownum <= 20
minus
select rownum,department_id,department_name from departments where rownum < 11;
ROWNUM DEPARTMENT_ID DEPARTMENT_NAME
11 110 Accounting
12 120 Treasury
13 130 Corporate Tax
14 140 Control And Credit
15 150 Shareholder Services
16 160 Benefits
17 170 Manufacturing
18 180 Construction
19 190 Contracting
20 200 Operations
10 rows selected.

For each row returned by a query, the ROWNUM pseudocolumn returns a number indicating the order in which Oracle selects the row from a table or set of joined rows. The first row selected has a ROWNUM of 1, the second has 2, and so on.
Conditions testing for ROWNUM values greater than a positive integer are always false. For example, this query returns no rows:
SELECT * FROM employees
WHERE ROWNUM > 1;
You can get the selected records based on the rownum using the inline query....
SQL> select rownum, empno from emp;
ROWNUM EMPNO
1 7369
2 7499
3 7521
4 7566
5 7654
6 7698
7 7782
8 7788
9 7839
10 7844
11 7876
ROWNUM EMPNO
12 7900
13 7902
14 7934
14 rows selected.
SQL> select * from (select rownum rn, empno from emp) where rn > 2 and rn < 5;
RN EMPNO
3 7521
4 7566

Needs help to retrive the last row in a select query without using rownum

Hi ,
i need to retrive the last row from the select sub query without using rownum.
is there any other way to retrive the last row other than the below query.
is that the ROWNUM=1 will always retrive the 1 row of the select query ?
select from*
*(select ename from employee where dept_id=5 order by desc) where rownum=1;*
Please advise.
thanks for your help advance,
regards,
Senthur

957595 wrote:
Actually my problem is ithat while selecting the parents hiearchy of the child data using
CONNECT BY PRIOIR query
I need the immediate parent of my child data.
For example my connect BY query returns
AAA --- ROOT
BBB --PARENT -2
CCC --PARENT-1
DDD IS my input child to the connect by query
Immediate parent of my child data "DDD" ---> CCC(parent -1)
i want the data "CCC" from the select query,for that i am taking the last row of the query with rownum.
I got to hear that using ROWNUM to retrive the data will leads to some problem.It is a like a magic number.I am not sure what the problem will be.
So confusing with using this rownum in my query.
Please advice!!!It's not quite clear what you're wanting, but perhaps this may help?
you can select the PRIOR values to get the parent details if you want...
SQL> ed
Wrote file afiedt.buf
1 select empno, lpad(' ',(level-1)*2,' ')||ename as ename, prior empno as mgr
2 from emp
3 connect by mgr = prior empno
4* start with mgr is null
SQL> /
     EMPNO ENAME                                 MGR
      7839 KING
      7566   JONES                              7839
      7788     SCOTT                            7566
      7876       ADAMS                          7788
      7902     FORD                             7566
      7369       SMITH                          7902
      7698   BLAKE                              7839
      7499     ALLEN                            7698
      7521     WARD                             7698
      7654     MARTIN                           7698
      7844     TURNER                           7698
      7900     JAMES                            7698
      7782   CLARK                              7839
      7934     MILLER                           7782
14 rows selected.(ok, not the best of examples as the mgr is already known for a row, but it demonstrates you can select prior data)

How am I able to use an injected EJB in a Managed Bean Constructor?

JSF 1.2
EJB 3.0
Glassfish v1
Summary:
Managed bean injected EJB is null when referencing EJB var in constructor.
Details:
In my managed bean, I have a constructor that tries to reference an injected EJB, such as:
public class CustomerBean implements Serializable {
@EJB private CustomerSessionRemote customerSessionRemote;
public CustomerBean() {
List<CustomerRow> results = customerSessionRemote.getCustomerList();
}The call within the constructor to customerSessionRemote is null - I've double checked this in Netbeans 5.5.
How am I able to use an injected EJB in a Managed Bean Constructor?
Thanks,
--Todd

OK, I was reading the article Web Tier to Go With Java EE 5: A Look at Resource Injection and I understand your statement too.
Is there any way possible to Inject the EJB prior to the bean instance creation at all?
Maybe, I need to approach it with the old fashion Java EE 1.4 route and using JNDI in the PostConstruct annotated method to reference the EJB in the managed bean.
This had to been thought out before, I don't understand why a manged bean's life cycle places any injections at the end of the bean creation.
Also, now that I understand that the @PostConstruct annotated method will be called by the container after the bean has been constructed and before any business methods of the bean are executed.
I am trying to reference my EJB as part of the creation of the managed bean.
What happens: the JSF page loads the managed bean and I need to populate a listbox component with data from an EJB.
When I try to make the call to the EJB in the listbox setter method, the EJB reference is null.
Now, I'm not for sure if the @PostConstruct annotation is going to work... hmmmm.
** Figured it out. ** I just needed to move the EJB logic that was still in the setter of the component I wanted to populate into the annotated PostConstruct method.

Do i have to use JNDI with EJBS?

Hi
I want to use JNDI to lookup a system which i will send messages to using JMS. I would like to have some java classes on Tomcat to do the job. But...whenever i hear about JNDI it is always in relation to EJBs. Can i only use JNDI with EJBS?
If i can use JNDI is there anything important i need to know about.
Thanks in advance!
San H.

You can definitely use JNDI outside of EJB's - in particular, it's a great interface for dealing with LDAP servers, even securely, and can also be used for DNS interfacing, COS, RMI registries, etc.
While JNDI was chosen as the method by which J2EE components can locate other components in a distributed environment, it's by no means limited to that task :) It's a wonderful API, and in terms of things you need to know, most everything is covered fairly well at the JNDI tutorial in the various trails that are mapped out there.
http://java.sun.com/products/jndi/tutorial/
Good luck!
James
James Manning | Principal Engineer
Porivo Technologies, Inc.
919.806.0566 | [email protected]
http://www.porivo.com/
Measuring end-to-end Web performance.
Register for a FREE Performance appraisal:
http://www.porivo.com/peerReview/eval.html

Do i have to use JMS with EJBS?

Hi
I want to use JMS as a messaging system (a queue) between my system and someone elses. I would like to have some java classes on Tomcat to do the job. But...whenever i hear about JMS i always hear it in relation to EJBs. Can i only use JMS with EJBS?
If i can use JMS is there anything important i need to know about.
Thanks in advance!
San H.

As far as I understand you are use JNDI and JMS is not bound with EJB's. These are java API's which are independent. Like JDBC you can use with Servlets, Applets, standalone applications, EJB, JMS etc etc.......
In the same way you can use JNDI and JMS with diferent API. And the important feature of Java is that all java API interact with each other when these are independent. I would appricate comments of everyone......................Thanks

Using ROWNUM in ODI

hey,
i want to use ROWNUM in my target table (DAYS) like:
Field 1(rownum) Field2
1 Monday
2 Tuesday
i create a field in my target table and in the mapping i use ROWNUM but it doesnt work.
Thanks for ur help
Mehdi

Hi,
I think you want to use a sequence generated number for the first column right?
In that case : from my understanding to what you have posted -
Step-1 : Create a Procedure and pass the code under 'Details' tab,before this check the right Technology
Step-2: Create a Scenario,select Native Sequence --> click the correct Schema and check Development --> the created procedure name shows up --> click OK
Step-3 : Go to Mapping, open Expression editor for that Particular Column, click the Project Sequences and you will find the created Sequence. drag and drop in the editor
Now run the interface, you will get the desired result. it will generate the sequence num for that particular column
Regards,
M

Using rownum in EJB-QL ..Pagination using CMP 2.1

Similar Messages

Maybe you are looking for