如果在循环PL SQL中满足条件，如何退出程序

Question

Let's say I have a for loop

for i in array.first .. array.last loop
 boolean := c(i) > d(i);
 if boolean --is true then
 exit the loop immediately and also exit the entire procedure

 else if the boolean is never true til the end of the loop, exit the loop
 and keep running other scripts in this procedure.

I know the 'EXIT' keyword needs to be inside of the loop in order to exit the loop if condition is met. And 'RETURN' needs to be outside of the loop, to exit the procedure.

But if I put 'RETURN' outside of the loop, then I think no matter what the result is from the loop, it will exit the entire procedure when the loop ends?

Answer 1

If you want to be didactic about it, you should use an EXIT to get out of the loop, then use a RETURN to exit from the procedure (duplicating any necessary tests), thus following the structured programming rule that "A procedure should only have a single entrance and a single exit". In practice 99.999% of programmers would just code the RETURN inside the body of the loop because A) it's clearer as to what's going on (you're not just getting out of the loop, you're returning from the procedure), and B) it's shorter. Do as you will. Best of luck.

Answer 2

The simple loop. It's called simple for a reason: it starts simply with the LOOP keyword and ends with the END LOOP statement. The loop will terminate if you execute an EXIT, EXIT WHEN, or RETURN within the body of the loop (or if an exception is raised).

See Oracle Magazine

Answer 3

Following through with Tamás Kecskeméti 's link , the only recommended way is to use a while loop with the desired condition specified in the beginning itself.

Below is and excerpt from the above link :

Code Listing 5: A WHILE loop with one exit 

PROCEDURE display_multiple_years (
   start_year_in   IN PLS_INTEGER
 , end_year_in     IN PLS_INTEGER)
IS
   l_current_year PLS_INTEGER := start_year_in;
BEGIN
   WHILE ( l_current_year <= end_year_in
         AND total_sales_for_year (l_current_year) > 0)
   LOOP
      display_total_sales_for_year (l_current_year);
       l_current_year := l_current_year + 1;
   END LOOP;
END display_multiple_years;

Answer 4

define an exception, and when ever you want to exit raise and handle the exception as

    create procedure exit_loop_example as
    exit_loop_exception exception;
    begin
/* previous code block */
begin
    for i in 1..20 loop
     raise exit_loop_exception;
    end loop;
    exception when 
    exit_loop_exception then
    /* handle exit loop*/
    null;
    end;
/* next code block */
end;