有关数据库SQL递归查询在不同数据库中的实现方
本文给大家介绍有关数据库SQL递归查询在不同数据库中的实现方法,具体内容请看下文。
比如表结构数据如下:
Table:Tree
ID Name ParentId
1 一级 0
2 二级 1
3 三级 2
4 四级 3
SQL SERVER 2005查询方法:
//上查 with tmpTree as ( select * from Tree where Id=2 union all select p.* from tmpTree inner join Tree p on p.Id=tmpTree.ParentId ) select * from tmpTree //下查 with tmpTree as ( select * from Tree where Id=2 union all select s.* from tmpTree inner join Tree s on s.ParentId=tmpTree.Id ) select * from tmpTree
SQL SERVER 2008及以后版本,还可用如下方法:
增加一列TID,类型设为:hierarchyid(这个是CLR类型,表示层级),且取消ParentId字段,变成如下:(表名为:Tree2)
TId Id Name
0x 1 一级
0x58 2 二级
0x5B40 3 三级
0x5B5E 4 四级
查询方法:
SELECT *,TId.GetLevel() as [level] FROM Tree2 --获取所有层级 DECLARE @ParentTree hierarchyid SELECT @ParentTree=TId FROM Tree2 WHERE Id=2 SELECT *,TId.GetLevel()AS [level] FROM Tree2 WHERE TId.IsDescendantOf(@ParentTree)=1 --获取指定的节点所有下级 DECLARE @ChildTree hierarchyid SELECT @ChildTree=TId FROM Tree2 WHERE Id=3 SELECT *,TId.GetLevel()AS [level] FROM Tree2 WHERE @ChildTree.IsDescendantOf(TId)=1 --获取指定的节点所有上级
ORACLE中的查询方法:
SELECT * FROM Tree START WITH Id=2 CONNECT BY PRIOR ID=ParentId --下查 SELECT * FROM Tree START WITH Id=2 CONNECT BY ID= PRIOR ParentId --上查
MYSQL 中的查询方法:
//定义一个依据ID查询所有父ID为这个指定的ID的字符串列表,以逗号分隔 CREATE DEFINER=`root`@`localhost` FUNCTION `getChildLst`(rootId int,direction int) RETURNS varchar(1000) CHARSET utf8 BEGIN DECLARE sTemp VARCHAR(5000); DECLARE sTempChd VARCHAR(1000); SET sTemp = '$'; IF direction=1 THEN SET sTempChd =cast(rootId as CHAR); ELSEIF direction=2 THEN SELECT cast(ParentId as CHAR) into sTempChd FROM Tree WHERE Id=rootId; END IF; WHILE sTempChd is not null DO SET sTemp = concat(sTemp,',',sTempChd); SELECT group_concat(id) INTO sTempChd FROM Tree where (direction=1 and FIND_IN_SET(ParentId,sTempChd)>0) or (direction=2 and FIND_IN_SET(Id,sTempChd)>0); END WHILE; RETURN sTemp; END //查询方法: select * from tree where find_in_set(id,getChildLst(1,1));--下查 select * from tree where find_in_set(id,getChildLst(1,2));--上查
补充说明:上面这个方法在下查是没有问题,但在上查时会出现问题,原因在于我的逻辑写错了,存在死循环,现已修正,新的方法如下:
CREATE DEFINER=`root`@`localhost` FUNCTION `getChildLst`(rootId int,direct【文章出处:香港服务器】ion int) RETURNS varchar(1000) CHARSET utf8 BEGIN DECLARE sTemp VARCHAR(5000); DECLARE sTempChd VARCHAR(1000); SET sTemp = '$'; SET sTempChd =cast(rootId as CHAR); IF direction=1 THEN WHILE sTempChd is not null DO SET sTemp = concat(sTemp,',',sTempChd); SELECT group_concat(id) INTO sTempChd FROM Tree where FIND_IN_SET(ParentId,sTempChd)>0; END WHILE; ELSEIF direction=2 THEN WHILE sTempChd is not null DO SET sTemp = concat(sTemp,',',sTempChd); SELECT group_concat(ParentId) INTO sTempChd FROM Tree where FIND_IN_SET(Id,sTempChd)>0; END WHILE; END IF; RETURN sTemp; END
这样递归查询就很方便了。