Synchronous Update 

In synchronous update, you do not submit update requests using CALL FUNCTION … IN UPDATE TASK . Instead you use the ABAP statement COMMIT WORK AND WAIT. When the update is finished, control passes back to the program. Synchronous update works in the same way as bundling update requests in a subroutine (PERFORM ON COMMIT). This kind of update is useful when you want to use both asynchronous and synchronous processing without having to program the bundles in two separate ways. The following diagram illustrates the synchronous update process:

Use this type of update whenever the changed data is required immediately. For example, you may want to link SAP LUWs together where one LUW depends on the results of the previous one.