这篇文章主要介绍了MySql如何利用父id递归向下查询子节点,具有一定借鉴价值,感兴趣的朋友可以参考下,希望大家阅读完这篇文章之后大有收获,下面让小编带着大家一起了解一下。
不用写存储过程,不用建数据库函数,一段sql就可以实现
SELECTID.LEVEL,DATA.* FROM(SELECT@ids AS _ids,( SELECT @ids := GROUP_CONCAT( region_id ) FROM region WHERE FIND_IN_SET(parent_id, @ids ) ) AS cids,@l := @l + 1 AS LEVEL FROMregion,( SELECT @ids := 3, @l := 0 ) b WHERE@ids IS NOT NULL ) ID,region DATA WHEREFIND_IN_SET( DATA.region_id, ID._ids ) ORDER BYLEVEL
测试
--创建测试环境create table t_test(id int PRIMARY key,parent_id int,name varchar(200))insert t_test VALUES(1,null,"中国");insert t_test VALUES(2,1,"华北");insert t_test VALUES(3,2,"山西省");insert t_test VALUES(4,2,"北京");insert t_test VALUES(5,3,"临汾市");insert t_test VALUES(6,4,"北京市");insert t_test VALUES(7,5,"尧都区");insert t_test VALUES(8,6,"朝阳区");insert t_test VALUES(9,7,"解放西路");insert t_test VALUES(10,8,"朝阳北路");SELECT * FROM t_test;
测试数据展示
查询 id=1,查询中国下边有哪些地方
SELECTID.LEVEL,DATA.* FROM(SELECT@ids AS _ids,( SELECT @ids := GROUP_CONCAT( id ) FROM t_test WHERE FIND_IN_SET(parent_id, @ids ) ) AS cids,@l := @l + 1 AS LEVEL FROMt_test,( SELECT @ids := 1, @l := 0 ) b WHERE@ids IS NOT NULL ) ID,t_test DATA WHEREFIND_IN_SET( DATA.id, ID._ids ) ORDER BYLEVEL
id=3,查询山西下边有哪些地方
SELECTID.LEVEL,DATA.* FROM(SELECT@ids AS _ids,( SELECT @ids := GROUP_CONCAT( id ) FROM t_test WHERE FIND_IN_SET(parent_id, @ids ) ) AS cids,@l := @l + 1 AS LEVEL FROMt_test,( SELECT @ids := 3, @l := 0 ) b WHERE@ids IS NOT NULL ) ID,t_test DATA WHEREFIND_IN_SET( DATA.id, ID._ids ) ORDER BYLEVEL
id=4,查询北京下边有哪些地方
最后再从 id=2 华北地区往下查询
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