Oracle if updating
Often this problem is solved with a select statement and then an IF statement, eg: declare v_exists varchar2(1) := ' F'; begin begin select ' T' into v_exists from employee where employee_id := i_employee_id; exception when no_data_found then null; end; if v_exists = ' T' then update employee set ... When coding a procedure, you should try and get an idea of how the procedure will be used.
where employee_id = i_employee_id else insert ( ... In this case, the question to ask whether the procedure will mostly be used to update existing employee records, or insert new ones.
This is what I have attempted but seems to be technically wrong.
A frequent occurrence when writing database procedures is to handle a scenario where given a set of fields, for example a new employee record, update the existing employee record if it exists otherwise create it.
If the more likely case is that existing records will be updated, the code below is better: begin update employees set ....
where employee_id = i_employee_id; if sql%rowcount = 0 then -- no rows were updated, so the record does not exist insert into employees ( ... ); end if; end; When any SQL statement is executed in PLSQL, the SQL%ROWCOUNT variable will contain the number of rows affected (in this case updated) by the most recent query. The MERGE statement takes a list of records which are usually in a staging table, and adds them to a master table.
Two popular reasons to use compound trigger are: Hopefully this example with make things more clear. NAME IS NULL) ) THEN v_index := v_index 1; v_emp_changes(v_index).upd_dt := SYSDATE; v_emp_changes(v_index).upd_by := SYS_CONTEXT (' : NEW. So that same computation is not made during after-each-row section, and is computed and stored in a variable just once before row-level execution begins.This common state is established at the start of triggering statement and is destroyed after completion of trigger (regardless of trigger being in error or not). SALARY IS NULL) ) THEN v_index := v_index 1; v_emp_changes(v_index).upd_dt := SYSDATE; v_emp_changes(v_index).upd_by := SYS_CONTEXT (' Now any changes in any field of employees will to be written in aud_emp table.If same had to be done without compound-trigger, it might have been required to share data using packages. A beauty of this approach is we were able to access same data ‘v_emp_changes’ between statement and row triggering events.In this case, if it contain zero, it means the update failed to find any rows to update and therefore the record needs to be inserted instead. If the record exists in the master table, it should be updated with the new values in the staging table, otherwise insert the record from the staging table.Sounds pretty similar the problem outlined above, except that merge wants the new records to be in a staging table.