mysql 树状表数据查询

1语句中定义变量

SELECT

*

FROM

department

WHERE

id IN(

SELECT id

FROM department

WHERE id = 4

UNION(

SELECT id FROM

(

SELECT id,parent_id

FROM department

ORDER BY

parent_id,id

) depart_sorted,

(SELECT @pv := 4)

initialisation

WHERE find_in_set(parent_id,@pv)

AND length(@pv:=concat(@pv,',',id))

)

);

tips:如果id为字符串可能会出现 Illegal mix of collations (utf8_unicode_ci,IMPLICIT) and (utf8_general_ci,IMPLICIT) 错误

可以在find_in_set(parent_id,@pv 后添加 COLLATE utf8mb4_unicode_ci

2写数据库函数通过函数查询

函数

create function getRoles(roleId INT)

returns varchar(4000)

BEGIN

DECLARE oTemp VARCHAR(4000);

DECLARE oTempChild VARCHAR(4000);

SET oTemp = '';

SET oTempChild = CAST(roleId AS CHAR);

WHILE oTempChild IS NOT NULL

DO

SET oTemp = CONCAT(oTemp,',',oTempChild);

SELECT GROUP_CONCAT(id) INTO oTempChild FROM yzm_talks_role WHERE FIND_IN_SET(parent_id,oTempChild) > 0;

END WHILE;

RETURN oTemp;

END

调用

SELECT *

FROM yzm_talks_role

WHERE FIND_IN_SET(parent_id,getRoles(#{id}))

3程序内处理

查询id,parant_id到程序中,通过程序处理

获取树形结构所有子节点

oracle中有connect by prior可以使用