Looping thru merge statement

Question

I have a merge statement, this executes for all the rows when the procedure is executed. Here i would like to include this merge statement as the part of LOOP so that all records will not get updated for a one time.
how can i change this merge statement to include as the part of LOOP here.
the user id should be the key to update the table USERS in merge statement, the same user id is exists in the bulk collect too..
BEGIN
v_sysdate:= pkg_utilities.fn_sysdate(1) ;
o_Error_Text := 'ORA-Error in updating end date in user_status table ';
tname:= 'user_status';
     MERGE INTO user_status r1
     USING (
          SELECT rowid rid , lead(start_period) OVER (PARTITION by user_id
          order by start_period)- 1 new_enddate FROM user_status ) r2
     ON ( r1.rowid = r2.rid )
     WHEN MATCHED THEN
     UPDATE SET end_period = new_enddate ;
     OPEN generic_cv4
     FOR SELECT
     user_id,user_status_type_id
     FROM user_status
     WHERE end_period IS NULL;
LOOP
FETCH generic_cv4 BULK COLLECT INTO
v_user_id_seq,
v_user_status_new
LIMIT p_array_size;
EXIT WHEN v_user_id_seq.COUNT = 0;
IF v_user_id_seq.COUNT > 0 THEN
     o_Error_Text := 'ORA-Error in update user_status type id in users table ';
     tname:= 'users';
FORALL I IN v_user_id_seq.FIRST..v_user_id_seq.LAST
UPDATE users
SET user_status_type_id = v_user_status_new(i),
last_upd_date = v_sysdate
WHERE user_id = v_user_id_seq(i);
END IF;
COMMIT;
END LOOP;
v_user_id_seq.delete;
v_user_status_new.delete;
EXCEPTION
WHEN OTHERS THEN
DBMS_OUTPUT.PUT_LINE('Error' ||sqlerrm);
DBMS_OUTPUT.PUT_LINE(o_Error_Text);
v_sql_err :=SQLERRM;
ROLLBACK;
pkg_champ_message_log.champ_message_log ('PKG_MIGRATE_V1_NESTED_MEMBER.p_update_member_status', tname, null,'Nested', v_sql_err,'Error',o_Error_Text,O_STATUS);
END;

Answer 1

Now lets talk how can i keep this merge statemnet as the part of the loop. It seems your mind is made up.
Unfortunately, what you're asking makes no sense at all. You can't "loop through a merge statement".
If you don't want to use merge for the entire table at once, the only thing you can do is to break up the table in your USING clause by some sort of range (maybe an account number or whatever). You could then run your code for each range (or even run them in parallel).
The only other option is to not use MERGE at all and duplicate the logic of it within your loop (which is what I said in my first response).