Try to raise message type 'S'. if you raise message type 'E' will stop program.
Then these info will write to job log
Ex:
Loop at it_mara.
update to table mara.
If sy-sy-subrc = 0
message 'success material created' TYPE 'S'
else.
message 'error rejected TYPE 'S'
endloop
Perform some search on Application Log in online help and sample reports like SBAL_DEMO_*.
Then adapt your creation program and allow users to transaction SLG1.
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