Using Statements With Stored Procedures In SQLJDBC 1.2

Hi,

I am doing some research on sqljdbc 1.2. I have run into a few problems with the jdbc driver. I think it would be so much easier just to ask the expert here.

1. when to use CallableStatment, PreparedStatement, Statement for stored proc and why?
http://msdn2.microsoft.com/en-us/library/ms378046.aspx
talks about using Statements with Stored Procedures.
It says for stored Proc with no param, use Statement; for stored proc with only input param, use PreparedStatement; and for stored proc with output param, return status or update count, use CallableStatement.
Is there any special considerations to select which one to use, is there any performance differences? I assume we can always use CallableStatement for stored proc.

2. mutliple statements on one Connection
The JDBC spec allows multiple Statement on one Connection with no need to close the previous Statment. When Connection.close() is called, all the Statements and ResultSets will be closed too.
I tried with regular stored proc, it is fine of have a CallableStatement, then a Statement, without close the CallableStatment, all the Statements are executed with no error.
However, when I change the stored proc, using explicit transaction, i.e BEGIN TRANSACTION, and COMMIT TRANSACTION, the Statement failed and throw an error:
com.microsoft.sqlserver.jdbc.SQLServerException: Server failed to resume the transaction, desc: 3500000001.
at com.microsoft.sqlserver.jdbc.SQLServerException.makeFromDatabaseError(Unknown Source)
at com.microsoft.sqlserver.jdbc.SQLServerStatement.getNextResult(Unknown Source)
at com.microsoft.sqlserver.jdbc.SQLServerStatement.doExecuteStatement(Unknown Source)
at com.microsoft.sqlserver.jdbc.SQLServerStatement$StmtExecCmd.doExecute(Unknown Source)
at com.microsoft.sqlserver.jdbc.TDSCommand.execute(Unknown Source)
at com.microsoft.sqlserver.jdbc.SQLServerConnection.executeCommand(Unknown Source)
at com.microsoft.sqlserver.jdbc.SQLServerStatement.executeCommand(Unknown Source)
at com.microsoft.sqlserver.jdbc.SQLServerStatement.executeStatement(Unknown Source)
at com.microsoft.sqlserver.jdbc.SQLServerStatement.executeQuery(Unknown Source)

When I add a CallableStatement.close() before the create the second Statment, then it worked. Is this a bug or something special needs to be set for stored proc with Transaction?

3. Statement.getGeneratedKeys
Under the hood, is it making another round trip to get the generatedkeys, or when the Statement created with Statement.RETURN_GENERATED_KEYS is excuted, the identity field is already retured with the Statement?

This method call works with regular insert Statement, but does not work for PreparedStatement calling a stored proc. Is this a bug?

Thanks in advance,

jessica