Mapping Entity beans to existing database tables.

Hi All,
I am using the RI of the J2EE (1.3.1) server provided by SUN. While deploying an entity bean I don't want to create a table by default, I want it to map to an existing table in the database. I find no DB column/EJB field mapping facility in the deploytool.
Is it not possible or am I missing something....
Thx n Rgds
Lorenzo

Hi!
I'm using a different J2EE server (OC4J). But got this from the J2EE RI guide.
If you do not want the container to create the table during deployment, follow these steps:
1. In the Application Deployment Tool, select the Entity tab of the entity bean.
2. In the Entity tabbed pane, click Deployment Settings.
3. In the Deployment Settings dialog box, de-select the checkbox for "Create Table on Deploy."
HTH.

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Message was edited by:
Deddiekoel

Can we create external table from an existing database table ?

Hi everyone,
As i understand, its possible to create a new table based on an existing table without copying any values from it, using the following command;
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http://download.oracle.com/docs/cd/B19306_01/server.102/b14220/utility.htm#sthref1800
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Container Managed Persistence entity bean relationship fields

I want to ask something that until now still confuse. Did Relationship fields in Container Managed Persistence entity beans declare , inside Database table or only Persistence fields .
If Relationship fields not declare inside database table ,how if SQL calls the relationship fields between related entity bean.
did container handle this task.
example: I have 2 entity bean with CMP(Container Managed Persistence)version 2.0
call Player and Team. every entity bean have own relationship fields and persistence fields.
player has playerId(primary key),name,position,age persistence fields and teams is relationship fields.
team has teamId(primary key),name,city and players is relationship fields.
I know that all persistence fields is declare in own database table but how about relationship fields.
can you tellme, How SQL calls can access relationship fields if relatiosnship fields is not declare in database table.
I use J2EE RI SDK version 1.3
and deploytool .
thank's .

thank's for your reply .Now I have another problem
I use J2EE RI from java.sun .I try to follow example in j2eetutorial about CMP Example call RosterApp.ear .
I dont'change anything code inside RosterApp.ear but when I deploy and runclient command thereis syntax error :
java.rmi.ServerException: Remote exception occured in server thread :nested exception is java.rmi.ServerException :exception thrown from bean :nested exception is : java.ejb.EJBException :nested exception is :java.sql.SQLException :syntax error or access violation ,message from server: "you have an error in SQL syntax near "
"leagueBeanTable" WHERE "leagueId" = 'L1' at line 1
in example ,RosterApp.ear use Cloudscape database ,but I try to use Mysql database for RosterApp.ear ,is there any different syntax SQL from Cloudscape to Mysql .
if like that ,so I must edit first SQL calls from Cloudscape to MYSQL . I think because relationship fields is for entity beans only ,so how if mysql database want to access foreign key another table because foreign key isn't declare in databse table.
example : I have 3 entity bean call player, team, league .
1. PlayerEJB have persistence fields name, position, playerId(primary key), cmr fields is teams
2. TeamEJB have persistence fields name, city, teamId (primary key) , cmr fields is players and leagues .
3. LeagueEJB have persistence fields name ,sport, leagueId(primary key), cmr fields is teams
so table is
PlayerEJB <--->TeamEJB<--->LeagueEJB
Player have some finder method call findBySport(String Sport) .
because Sport is persistence fields for LeagueEJB
so PlayerEJB must traverse TeamEJB first before LeagueEJB
EJB QL : SELECT distinct object(p) FROM Player (p) IN (p.teams) AS t
WHERE t.league.sport = ?1
I know that Container will translates EJB QL to SQL calls ,but default is only for cloudscape database and I use for MYsql .
so can you helpme how to query method findBySport(String sport) to Mysql calls .
thereis no foreign key between table in database table there is only Relationship fields in entity bean.

Problems accessing tables in oracle database with ejb entity bean

I have created a simple server application that uses an entity bean (version 2.0) for an existing table in oracle database, and a session bean that is used as an outside interface for performing operations on that table.
after deploying the server and client application the client attempts to perform an operation with the session bean remote interface it obtained.
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the table of course exists, and the username password I'm using has all the permissions needed for this table.
note - I'm using the Forte enterprise edition 4.0 as developer tool.
I'll be glad to get some help.
Here is the full stack trace of the exception:
javax.ejb.TransactionRolledbackLocalException: Exception thrown from bean; nested exception is: javax.ejb.EJBException: nested exception is: java.sql.SQLException: ORA-00942: table or view does not exist
javax.ejb.EJBException: nested exception is: java.sql.SQLException: ORA-00942: table or view does not exist
java.sql.SQLException: ORA-00942: table or view does not exist
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Well it seems like the problems has a simple explanation. The Forte assigns a default table name (<entityName>EJBTable) when creating an entity bean from an existsing table in DB (which is not the same as the one it was created from !!!). Also, for reason unknown, when you deploy these entity beans, it doesn't even create the new table under its new name (even if instructed to).
So using the Forte we managed to use successfuly only entity beans that were created "from scretch" (when deployed their tables are created).
Does anyone know how to change the default name the Forte uses, and make it work properly with entity beans created from an existsing table (without going over the xml's) ?

Should ADF Entity Object Map to Database Table or View?

We are building a new 3-tier JClient/ADF application. We have mapped most entity objects directly to database tables. Now that we are preparing to deploy, our DBA is angry; he believes that all entity objects should be mapped to database views. The developers see this as a headache, UML can not forward/reverse changes, and now we have another layer of abstraction, which doesn't seem to serve a useful purpose. What is the best practice in a new 3-tier application?

Hi,
I'm still having problems but I found out why these tables are returning errors. The username I've been given by the DBA to connect to the database is CONSULTA, but this user is only for querying purposes, the actual objects reside on a differente schema, of course, which is PROD. So the line:
"CONSULTA"."ESTADOS"@"PROD@AYADEV_LOCATION" "ESTADOS"
raises an exception because the table ESTADOS is not located on that schema, but on PROD. If I query the table from SQL Plus with:
SELECT *
FROM [email protected]@AYADEV_LOCATION
then there's no problem at all.
Why is this? How do I instruct OWB to point to the correct schema or to avoind fully qualifying the table name?
Please help me, I'm kind of confused here.
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Is it possible to map the cmp fields of the entity bean with out dictionary

Dear sirs,
I have created the EJB project module and WEB Module. Now i have to map the CMP fields of the entity bean to the underlying table. Is it possible to map the cmp fields of the entity bean with out java dictionary? If yes how can we do that.
I have got some error while mapping an EJB's CMP fields to the table through dictionary. I was actually intended to map 79 fields but it gives an error that more than 64 fields are not allowed while building the dictionary.
1. Can you tell me what could be the possible reason?
2. Is it possible to map the cmp fields of the entity bean with out java dictionary? If yes how can we do that.
Kindly helo me,
Sudheesh K S

Hi,
Sudheesh please check up if the below link helps,there are other ways of writing the persistent.xml for container managed entity bean.
http://help.sap.com/saphelp_nw04s/helpdata/en/9b/f695f0c84acf46a4e0b31f69d8a9b7/frameset.htm, probably in the studio you cannot browse through tables not in the java dictionary,but manually editing it may still solve the problem.
Also here is another link that specifies the databases supported by J2EE Engine.
http://help.sap.com/saphelp_nw04s/helpdata/en/66/a5283eeb47b40be10000000a114084/frameset.htm
The below link shows how to specify the database vendor and datasource
http://help.sap.com/saphelp_nw04s/helpdata/en/e1/67fc3ee241ba28e10000000a114084/frameset.htm
Hope you are able to solve the problem.
Do let us know if you come up with the solution.
Regards,
Harish
Message was edited by: HARISH SUBRAMANIAN

Mapping Entity beans to existing database tables.

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