How to traverse and check for values in internal table that already exist in the database?

[former_member1013685]

I am learning ABAP. I need to write a report program to display an error message if I am entering values from internal table that are already there in the database.

I have an internal table: i_tab that has records uploaded from a text file. It might also have some duplicate entries that are already in the database table: ztable. Now I need to insert these entries into the database. If all the entries are new, the program will simply add the new records to the database table ztable and display a success message "Successfully added". However, if there are duplicate entries in the internal table, it should display the erorr message "Duplicate entries". Let us say that there are 2 columns in the i_tab and ztable. Those are user_id and user_name. User_id is the primary key

How do I check for the same entires of i_tab with ztable and display the erorr message?

One way that I tried to do and did not work was :

Here in the below code the loop doesn't work and goes straight to insert table statement so it tries to append the duplicate values and then the program throws a runtime error and does not execute. If it worked, then it would display the error message and not move to the insert statement.

loop at i_tab into wa_tab.
    if ztable-user_id = wa_tab-user_id
       MESSAGE 'DUPLICATE ENTRIES' TYPE 'E'.
    endif.
endloop.

insert ztable from table i_tab.
if sy-subrc = 0.
    MESSAGE 'SUCCESSFULLY ADDED' TYPE 'S'.
endif.

[jerryjanda]

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[Sandra_Rossi]

If you use

INSERT ... FROM TABLE ... ACCEPTING DUPLICATE ENTRIES.

it will insert lines which are not duplicates, and it will return SY-SUBRC = 4 if there is at least one duplicate. See ABAP documentation for more information.