pl/sql中for loop

Oracle/PLSQL: FOR Loop

The syntax for the FOR Loop is:

FOR loop_counter IN [REVERSE] lowest_number..highest_number
LOOP
     {.statements.}
END LOOP;

You would use a FOR Loop when you want to execute the loop body a fixed number of times.

Let's take a look at an example.

FOR Lcntr IN 1..20
LOOP
     LCalc := Lcntr * 31;
END LOOP;

This example will loop 20 times. The counter will start at 1 and end at 20.

The FOR Loop can also loop in reverse. For example:

FOR Lcntr IN REVERSE 1..15
LOOP
     LCalc := Lcntr * 31;
END LOOP;

This example will loop 15 times. The counter will start at 15 and end at 1. (loops backwards);

 

and there is another use:

DECLARE
BEGIN
  FOR eno IN (SELECT empno AS id FROM emp WHERE emp.empno IN (7900, 7902))
  LOOP
    INSERT INTO new_emp
      (employee_id,
       NAME)
      SELECT t.empno,
             t.ename
        FROM emp t
       WHERE t.empno = eno.id;
    COMMIT;
  END LOOP;
END;