Question

我在mysql中的sproc中有动态查询的问题。

现在这个查询在我直接在phpmyadmin中执行时执行正常但是这似乎在执行时会出现语法错误。

BEGIN
SET @sql = 'set @my_id=24;
set @rank=0;
select * from ( 
    (
     select *, @rank:=@rank+1 as x from `list_content` where `id` > @my_id order by `id`)
     union (select *, @rank:=@rank+1 as x from `list_content` where `id` < @my_id order by `id`)
    ) `list_content` WHERE `listId` = 15 limit 4';

PREPARE stmt FROM @sql;
EXECUTE stmt;
DEALLOCATE PREPARE stmt;
END

我真的需要这个以某种方式工作，因为我需要通过我传递的参数更改一些字段名称。

我得到的执行错误是......

MySQL said: #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 'set @rank=0;
select * from ( 
    (
     select *, @rank:=@rank+1 as x from `list_c' at line 2

如果我可以在此环境之外执行它而没有任何问题，我认为这是一个准备查询的限制。

由于

Answer 1

正如prepared statements上的mysql手册所说：

预准备语句的SQL语法不支持多语句（即，单个字符串中的多个语句分隔; 字符）。

这意味着您在准备好的声明中不能有3个声明。但是，手册的同一部分也说明了

准备好的声明也是会议的全球性声明。

这意味着您可以将预处理语句之外的set语句移动到dtored proc的代码中，并且会话变量将在预准备语句中可用。

Answer 2

您需要声明分隔符，否则;将终止您的程序。像这样：

delimiter //
CREATE PROCEDURE whatever_you_named_it
BEGIN
SET @sql = 'set @my_id=24;
set @rank=0;
select * from ( 
    (
     select *, @rank:=@rank+1 as x from `list_content` where `id` > @my_id order by `id`)
     union (select *, @rank:=@rank+1 as x from `list_content` where `id` < @my_id order by `id`)
    ) `list_content` WHERE `listId` = 15 limit 4';

PREPARE stmt FROM @sql;
EXECUTE stmt;
DEALLOCATE PREPARE stmt;
END
//

然后，您可以使用

将分隔符设置回;

delimiter ;

Answer 3

将变量设置放入查询中。见@Shadow写的。

    SET @sql = 'select * from ( 
        (
         select *, @rank:=@rank+1 as x from `list_content` where `id` > @my_id order by `id`)
         union (select *, @rank:=@rank+1 as x from `list_content` where `id` < @my_id order by `id`)
        ) `list_content`
    CROSS JOIN (SELECT @my_id:=24, @rank:=0) as init
    WHERE `listId` = 15 limit 4';

存储过程 - 联合查询语法错误

3 个答案: