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mysql嵌套查询在过程中的替代方法_Mysql_Stored Procedures_Nested Query - Fatal编程技术网

mysql嵌套查询在过程中的替代方法

mysql嵌套查询在过程中的替代方法,mysql,stored-procedures,nested-query,Mysql,Stored Procedures,Nested Query,对于过程中的mysql嵌套查询有什么建议吗 CREATE DEFINER=`root`@`%` PROCEDURE `GET_PLACE_PARENT_CATEGORY`(IN paramCategoryId INT) BEGIN SELECT pc.place_parent_category_id, (SELECT pcc.place_category FROM place_category pcc WHERE pcc.place_category_id = pc.place_par

对于过程中的mysql嵌套查询有什么建议吗

CREATE DEFINER=`root`@`%` PROCEDURE `GET_PLACE_PARENT_CATEGORY`(IN paramCategoryId INT)
BEGIN
    SELECT pc.place_parent_category_id, (SELECT pcc.place_category FROM place_category  pcc WHERE pcc.place_category_id = pc.place_parent_category_id )
FROM place_category pc WHERE pc.place_category_id = paramCategoryId;
END

嵌套查询位于同一个表上。你确定这是对的? 我相信您需要两个表之间的简单联接。可能是这样的:

选择pc.place\u parent\u category\u id、pcc.place\u category 从place_类别pc 在pcc.place\u category\u id=pc.place\u parent\u category\u id上将place\u parent\u category作为pcc左连接
其中pc.place\u parent\u category\u id=paramCategoryId

用正确的方法重写查询,哪种方法有效?我的还是你的?你自己看,在两个问题前做一个解释