带有Prepared语句的MySQL存储过程不工作

我有以下存储过程：

CREATE PROCEDURE getLastValueAutomaticShelter(IN fieldName varchar(30), position_number INT)
BEGIN
SET @query = CONCAT('SELECT * FROM automatic_changes WHERE',fieldName,'IS NOT NULL AND P_id=?');
PREPARE stmt FROM @query;
SET @position_number=position_number;
EXECUTE stmt USING @position_number;
DEALLOCATE PREPARE stmt;
END

然后我运行它：

mysql> call getLastValueAutomaticShelter('current_level', 500)//

并获取以下错误：

ERROR 1064 (42000): 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 'NOT N
ULL AND P_id=?' at line 1

---

有什么想法吗？谢谢。

您需要在其中添加一些空格：

SET @query = CONCAT('SELECT * FROM automatic_changes WHERE ',fieldName,' IS NOT NULL AND P_id=?');
/*                                                  right ^ here....and ^ here*/

否则，您的最终查询可能如下所示：

SELECT * FROM automatic_changes WHEREcolumnameIS NOT NULL AND P_id='whatever';

你明白了：）