Updating an existing Row
Updating an existing row in a database table provides more opportunity for
concurrency and consistency errors than inserting a new row. Use techniques shown in this
section to help minimize the errors.
Using a work record SELECT ... FOR UPDATE SELECT...FOR UPDATE statement may be used to instruct the database server to lock the row that was selected. SELECT ... FOR UPDATE cannot be used outside of an explicit transaction. The locks are held until the end of the transaction.SCROLL CURSOR WITH HOLD SCROLL CURSOR to move through an SQL result set, updating or deleting the rows as needed. BDL cursors are automatically closed by the database interface when a COMMIT WORK or ROLLBACK WORK statement is performed. To allow the user to continue to scroll through the result set, the SCROLL CURSOR can be declared WITH HOLD, keeping it open across multiple transactions.Example: Updating a Row in the customer table custquery.4gl module to allow users to update existing rows in the customer table.Module custquery.4gl work_custrec record that can be used as working storage when a row is being updated.