请问ORACLE的代码换成PLPGSQL怎么写？

yangxinzhong

我刚接触postgresql，我要写一些过程，函数，请问下边的代码用plpgsql怎样写，谢谢

--------------------------------------ORACLE-------------------------------------------------------------

CREATE OR REPLACE PROCEDURE raise_salary (emp_id INTEGER, amount REAL) IS
   current_salary REAL;
   salary_missing EXCEPTION;
BEGIN
   SELECT sal INTO current_salary FROM emp
      WHERE empno = emp_id;
   IF current_salary IS NULL THEN
      RAISE salary_missing;
   ELSE
      UPDATE emp SET sal = sal + amount
         WHERE empno = emp_id;
   END IF;
EXCEPTION
   WHEN NO_DATA_FOUND THEN
      INSERT INTO emp_audit VALUES (emp_id, 'No such number');
   WHEN salary_missing THEN
      INSERT INTO emp_audit VALUES (emp_id, 'Salary is null');
END raise_salary;