I'm trying to write a script that will update a table in sysbase.
If it's failed then I want to rerun it one more time before exiting the script (fail due to bad value such as trying to put a string into datetime field or bad connection to the database)

Well my code below will always return exit 0 if the connection to the database is good.
How can I check to see if the update statement (SQL) is successful or not successful so I can rerun it again (loop it back).

Please advice.

Here is part of my code.

#!/bin/ksh

display_msg "\nSet start time to today date and till date to the end of previous month - logs into $LOGFILE"
connection_str="-S $SYBASE_SERVER -U $SYBASE_USERNAME -D $DATABASE"
isql $connection_str <<-ISQL_END | egrep -v "Password:" >> $LOGFILE 2>&1
$SYBASE_PASSWORD

update rls_job set start_time = '$logtime', till_date = '1'
go
ISQL_END
ret=$?

display_msg "Complete reset start time and till date - Return code = $ret"
let totalret=$totalret+$ret


echo `date +"%d.%m.%Y %H:%M:%S"`" End of script $0 with combined code = $totalret - logs in $LOGFILE" | tee -a $LOGFILE

if [ `grep "Msg" $LOGFILE | wc -l` -gt 0 ]; then
display_msg "Warning: Error detected in $LOGFILE"
exit 255
fi

exit $totalret