oracle pl sql 中的更新触发器问题

Question

I am creating an update trigger on a table called tax_table and inserting :new and :old values into update_audit_table . How can I incorporate related fields ( employee id from employee table) into update_audit_table in the same insert.

CREATE  UPDAT_TAX_TRIG 
AFTER UPDATE
   ON tax_table
   FOR EACH ROW
 BEGIN
   INSERT INTO update_audit_table(PREV_TAX_CODE, OLD_TAX_CODE)
   VALUES(:NEW.PREV_TAX_CODE, OLD:PREV_TAX_CODE);
END;

update_audit_table:

employee_id,
employee_name,
prev_tax_code,
old_tax_code

employee table :
employee_id,
employee_name

I am trying to include fields from employee table into update_audit_table while inserting audit record.

Answer 1

As you have currently described the tables, it is impossible as there is no correlation that has been described between the tax_table and the employee table that would let you join the two.

However, if we assume that tax_table has an employee_id column then you can use that:

CREATE  UPDAT_TAX_TRIG 
  AFTER UPDATE ON tax_table
  FOR EACH ROW
BEGIN
  INSERT INTO update_audit_table(
     employee_id,
     employee_name,
     PREV_TAX_CODE,
     OLD_TAX_CODE
  ) VALUES(
    :NEW.employee_id,
    (SELECT employee_name FROM employees WHERE employee_id = :NEW.employee_id),
    :NEW.PREV_TAX_CODE,
    :OLD.PREV_TAX_CODE
  );
END;
/

If it does not then you need to work out how the tax_table relates to an employee .