Question

我有一个简单的表：

mysql> select * from version;
+----+---------+
| id | version |
+----+---------+
|  1 | 1       |
+----+---------+
1 row in set (0.00 sec)

我需要创建一个存储过程，它将执行某些操作（或不执行任何操作），具体取决于此表的值（确切地说，是此表的唯一行）。

DELIMITER $$
DROP PROCEDURE IF EXISTS upgrade_version $$
CREATE PROCEDURE upgrade_version(current_version INTEGER, script TEXT)
BEGIN
  DECLARE version INT(11);
  SET version = (SELECT `version` FROM `version` WHERE `id` = 1 LIMIT 1);
  SELECT version;
  IF version = current_version + 1 THEN
    PREPARE upgrade_stmt FROM script;
    EXECUTE upgrade_stmt;
    UPDATE `version` SET `version` = `version` + 1 WHERE `id` = 1;
  ENDIF;
END $$
DELIMITER ;

在内部召唤：

CALL upgrade_version(1,'ALTER TABLE ...');

语法错误，mysql返回：

1064 - You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'script;
    EXECUTE upgrade_stmt;
    UPDATE `version` SET `version` = `version`' at line 7

有什么问题？

Answer 1

我不明白你为什么选择＆＃34; SELECT版本＆＃34;，如果你想选择你必须将它检索到varialbe的数据，那么当你在终端直接使用它时，该语句可以正常工作。你确定你的脚本中有prepared_stmt ..！？可能的解决方法是：

将varible name版本更改为version_v
而不是：

SET version =（SELECT version FROM version WHERE id = 1 LIMIT 1）;

SELECT版本;

试试这个：

SELECT `version` INTO Version_v FROM `version` WHERE `id` = 1 LIMIT 1);

Answer 2

试试这个：

DELIMITER $$
DROP PROCEDURE IF EXISTS upgrade_version $$
CREATE PROCEDURE upgrade_version(current_version INT, script TEXT)
BEGIN
  SELECT `version` into @ver FROM `version` WHERE `id` = 1 LIMIT 1;  
  SET @s = script;
  IF @ver = current_version + 1 THEN
    PREPARE upgrade_stmt FROM @s;
    EXECUTE upgrade_stmt;
    DEALLOCATE PREPARE upgrade_stmt;
    UPDATE `version` SET `version` = `version` + 1 WHERE `id` = 1;
  END IF;
END $$
DELIMITER ;

Answer 3

将值设置为声明变量

       DELIMITER $$
       create procedure Testing()
           begin
            declare Regione int;   
            set Regione=(select  id from users
            where id=1) ;
            select Regione ;
           end $$
         DELIMITER;

mysql存储过程从表中设置值

3 个答案:

将值设置为声明变量