Delete Operation in JDBC Sender Adapter not works

Question

Hi,
    I have one student table which contains the fields ID,Name,BirthMonth,BirthYear,ReadFlag fields. ReadFlag is a character field or lenght 1 which contains only values either 'Y' or ' '. 
     I want to execute delete operation in this table ie to delete the records which contains the readflag = 'Y'. So, I set the below values for the following parameters.
DELETE FROM student WHERE READFLAG = ' Y '
Query SQL Statement : SELECT * FROM student WHERE readflag = 'Y'
Update SQL Statement : DELETE FROM student WHERE READFLAG = 'Y'
Poll Interval : 60 Seconds.
    There are more records in this table which contains readflag = 'Y'. But, the Adapter does not delete those records from the table i.e delete operation is not executed. At the same time, in Comm. Channel monitoring it does not show any error, but the delete operation is not carried out in the table.
     I tried after 'COMMIT' the table also. But it does not work. What could be the reason ? or How to use Delete Operation effectively on the table ?
     Kindly help me friends to solve this problem.
Thanking you.
Kind Regards,
Jeg.

Answer 1

http://help.sap.com/saphelp_nw04/helpdata/en/7e/5df96381ec72468a00815dd80f8b63/content.htm >>>
<i>Adapter Work Method
You must add an indicator that specifies the processing status of each data record in the adapter (data record processed/data record not processed) to the database table.
The UPDATE statement must alter exactly those data records that have been selected by the SELECT statement. You can ensure this is the case by using an identical WHERE clause. (See Processing Parameters, SQL Statement for Query, and SQL Statement for Update below).
<b>Processing can only be performed correctly when the isolation level for transaction is set to repeatable_read or serializable.
Example
SQL statement for query: SELECT * FROM table WHERE processed = 0;
SQL statement for update: UPDATE table SET processed = 1 WHERE processed = 0;
processed is the indicator in the database.</b></i>
try with repeatable_read or serializable !!!
Also go thru this thread - DELETE Querey in JDBC SENDER