It seems that XBatchExecution is broken using the built in database. The 
following code fails in the addBatch line and kills OO. In order to run it, you 
must create and register an (empty) database named "playground":

Sub Main
  oDBCntxt = CreateUnoService("com.sun.star.sdb.DatabaseContext") 
  oDBSrc = oDBCntxt.getByName( "playground" ) 
  oConnection = oDBSrc.getConnection("","")
  msgbox "supportsBatchDataUpdates: " & 
oConnection.Metadata.supportsBatchUpdates()
  
  oStatement = oConnection.CreateStatement 

  sSQL =        "drop table TESTTABLE if exists; "
  sSQL = sSQL & "create table TESTTABLE (ID int IDENTITY, WKN char(20) );"
  oStatement.execute( sSQL) 
  
  sSQL = "insert into TESTTABLE ( WKN  ) values( 'abcWKN' );"
  oStatement.addBatch( sSQL) 'here it dies

  oStatement.executeBatch( sSQL) 

End Sub


The following codes wrok fine, however:
(i) 'normal' execute
Sub Main
  oDBCntxt = CreateUnoService("com.sun.star.sdb.DatabaseContext") 
  oDBSrc = oDBCntxt.getByName( "playground" ) 
  oConnection = oDBSrc.getConnection("","")
  msgbox "supportsBatchDataUpdates: " & 
oConnection.Metadata.supportsBatchUpdates()
  
  oStatement = oConnection.CreateStatement 

  sSQL =        "drop table TESTTABLE if exists; "
  sSQL = sSQL & "create table TESTTABLE (ID int IDENTITY, WKN char(20) );"
  oStatement.execute( sSQL) 
  
  sSQL = "insert into TESTTABLE ( WKN  ) values( 'abcWKN' );"
  oStatement.execute( sSQL) 

End Sub


and
(ii) prepared statement in batch mode
Sub Main
  oDBCntxt = CreateUnoService("com.sun.star.sdb.DatabaseContext") 
  oDBSrc = oDBCntxt.getByName( "playground" ) 
  oConnection = oDBSrc.getConnection("","")
  msgbox "supportsBatchDataUpdates: " & 
oConnection.Metadata.supportsBatchUpdates()
  
  oStatement = oConnection.CreateStatement 

  sSQL =        "drop table TESTTABLE if exists; "
  sSQL = sSQL & "create table TESTTABLE (ID int IDENTITY, WKN char(20) );"
  oStatement.execute( sSQL) 
  
  oPrepStmt =  oConnection.prepareStatement("insert into TESTTABLE ( WKN ) 
values( ? );")
  oPrepStmt.setString(1, "abcWKN")

  oPrepStmt.addBatch( ) 

  oPrepStmt.executeBatch() 

End Sub