对于MySQL中的循环例子 [英] For loop example in MySQL

问题描述

在MySQL中，我有这个存储过程与一个For循环：

  DELIMITER $$ 
 CREATE程序ABC（）
 
 BEGIN 
 DECLARE一个INT默认值为0; 
 simple_loop：LOOP 
 SET a = a + 1; 
选择一个; 
 IF a = 5 THEN 
 LEAVE simple_loop; 
 END IF; 
 END LOOP simple_loop; 
 END $$ 
  

总是打印 1 。什么是MySQL for循环的正确语法？

解决方案

  drop table if exists foo ; 
 create table foo 
（
 id int unsigned not null auto_increment primary key，
 val smallint unsigned not null default 0 
）
 engine = innodb; 
 
 drop procedure if exists load_foo_test_data; 
 
 delimiter＃
 create procedure load_foo_test_data（）
 begin 
 $ b declare v_max int unsigned default 1000; 
 declare v_counter int unsigned default 0; 
 
 truncate table foo; 
开始交易; 
，而v_counter< v_max do 
插入到foo（val）值（floor（0 +（rand（）* 65535）））; 
 set v_counter = v_counter + 1; 
结束; 
 commit; 
结束＃
 
分隔符; 
 
调用load_foo_test_data（）; 
 
 select * from foo order by id; 
  

In MySQL, I have this stored procedure with a For loop in it:

DELIMITER $$  
CREATE PROCEDURE ABC()

   BEGIN
      DECLARE a INT Default 0 ;
      simple_loop: LOOP
         SET a=a+1;
         select a;
         IF a=5 THEN
            LEAVE simple_loop;
         END IF;
   END LOOP simple_loop;
END $$

It always prints 1. What is the correct syntax for a MySQL for loop?

解决方案

drop table if exists foo;
create table foo
(
id int unsigned not null auto_increment primary key,
val smallint unsigned not null default 0
)
engine=innodb;

drop procedure if exists load_foo_test_data;

delimiter #
create procedure load_foo_test_data()
begin

declare v_max int unsigned default 1000;
declare v_counter int unsigned default 0;

  truncate table foo;
  start transaction;
  while v_counter < v_max do
    insert into foo (val) values ( floor(0 + (rand() * 65535)) );
    set v_counter=v_counter+1;
  end while;
  commit;
end #

delimiter ;

call load_foo_test_data();

select * from foo order by id;

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