mysql - 调用存储过程时出错

Question

当我调用我的过程时，它返回一个错误:

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 'NULL' at line 1

如何修复它，我的程序代码是否有错误？

这是我的存储过程:

DELIMITER $$
DROP PROCEDURE IF EXISTS `gamedb`.`ALIAS#SEARCH`$$
CREATE DEFINER=`root`@`localhost` PROCEDURE `ALIAS#SEARCH`(
  in section_id varchar(255),
  in category_id varchar(255),
  in content_id varchar(255)
)

BEGIN
declare q varchar(4000);
set @q = 'SELECT * FROM tbl_alias WHERE ALIAS_ACTIVE_STATUS=1';

IF section_id IS NOT NULL THEN
  set @q = concat(q,' AND ALIAS_SECTION_ID = ',section_id);
END IF;

IF category_id IS NOT NULL THEN
  set @q = concat(q,' AND ALIAS_CATEGORY_ID = ',category_id);
END IF;

IF content_id IS NOT NULL THEN
  set @q = concat(q,' AND ALIAS_CONTENT_ID = ',content_id);
END IF;

set @q= concat(q,' ORDER BY ALIAS_ID DESC');
prepare stmt from @q;

EXECUTE stmt;
DEALLOCATE PREPARE stmt;
END$$
DELIMITER ;

Answer 1

有几个问题

1. 由于您只能从用户变量中PREPARE，因此不需要局部变量q

2. 使用 CONCAT() 时，@q 变量缺少 @

   set @q = concat(q,' AND ALIAS_SECTION_ID = ',section_id);
                   ^
   

3. 由于您的 IN 参数定义为 VARCHAR，因此您最好在构建查询时引用它们的值

话虽这么说，你的 SP 可能看起来像这样

DELIMITER $$
CREATE PROCEDURE `ALIAS#SEARCH`(
  in section_id varchar(255),
  in category_id varchar(255),
  in content_id varchar(255)
)

BEGIN
  SET @q = 'SELECT * FROM tbl_alias WHERE ALIAS_ACTIVE_STATUS = 1';

  IF section_id IS NOT NULL THEN
    SET @q = CONCAT(@q, ' AND ALIAS_SECTION_ID = ''', section_id, '''');
  END IF;

  IF category_id IS NOT NULL THEN
    SET @q = CONCAT(@q, ' AND ALIAS_CATEGORY_ID = ''', category_id, '''');
  END IF;

  IF content_id IS NOT NULL THEN
    SET @q = CONCAT(@q, ' AND ALIAS_CONTENT_ID = ''', content_id, '''');
  END IF;

  SET @q = CONCAT(@q, ' ORDER BY ALIAS_ID DESC');

  PREPARE stmt FROM @q;
  EXECUTE stmt;
  DEALLOCATE PREPARE stmt;
END$$
DELIMITER ;