WHILE LOOP 语句会在判断条件结果为 TRUE 的时候，重复执行一序列语句。如果条件结果为 FALSE 了，则退出循环。语法格式如下：

WHILE condition LOOP
statement [, statement ]...
END LOOP;

注意：

如果 LOOP 和 END LOOP 之间的语句永远不改变，WHILE 后的条件结果为 FALSE ，则 WHILE LOOP 循环会一直重复不停止，直到强行中断子程序会话。

示例：使用 WHILE LOOP 语句

delimiter /
CREATE OR REPLACE PROCEDURE sp_test_while_loop
AS
    i_counter   number := 10;
BEGIN
    WHILE(i_counter > 0) LOOP 
        dbms_output.put_line('In the loop i_counter is ' || to_number(i_counter) );
        i_counter := i_counter - 1;
    END LOOP;
    dbms_output.put_line('Out of the loop i_counter is ' || to_number(i_counter) );
EXCEPTION 
    WHEN OTHERS THEN
        NULL;   
END;
/
delimiter ;
obclient>
obclient> set serveroutput on;
Query OK, 0 rows affected (0.00 sec)
obclient> call sp_test_while_loop();
Query OK, 0 rows affected (0.04 sec)
In the loop i_counter is 10
In the loop i_counter is 9
In the loop i_counter is 8
In the loop i_counter is 7
In the loop i_counter is 6
In the loop i_counter is 5
In the loop i_counter is 4
In the loop i_counter is 3
In the loop i_counter is 2
In the loop i_counter is 1
Out of the loop i_counter is 0
obclient>