现在大家应该都知道mysql版本中已经不支持直接的递归查询了，但是我们可以通过递归到迭代转化的思路是实现树的递归查询，接下来我们就一起去看看SQL实现MYSQL递归查询的方法。

创建表格

CREATE TABLE `treenodes` (

`id` int , -- 节点ID

`nodename` varchar (60), -- 节点名称

`pid` int -- 节点父ID

);

插入测试数据

INSERT INTO `treenodes` (`id`, `nodename`, `pid`) VALUES

('1','A','0'),('2','B','1'),('3','C','1'),

('4','D','2'),('5','E','2'),('6','F','3'),

('7','G','6'),('8','H','0'),('9','I','8'),

('10','J','8'),('11','K','8'),('12','L','9'),

('13','M','9'),('14','N','12'),('15','O','12'),

('16','P','15'),('17','Q','15'),('18','R','3'),

('19','S','2'),('20','T','6'),('21','U','8');

查询语句

SELECT id AS ID,pid AS 父ID ,levels AS 父到子之间级数, paths AS 父到子路径 FROM (

SELECT id,pid,

@le:= IF (pid = 0 ,0,

IF( LOCATE( CONCAT('|',pid,':'),@pathlevel) > 0 ,

SUBSTRING_INDEX( SUBSTRING_INDEX(@pathlevel,CONCAT('|',pid,':'),-1),'|',1) +1

,@le+1) ) levels

, @pathlevel:= CONCAT(@pathlevel,'|',id,':', @le ,'|') pathlevel

, @pathnodes:= IF( pid =0,',0',

CONCAT_WS(',',

IF( LOCATE( CONCAT('|',pid,':'),@pathall) > 0 ,

SUBSTRING_INDEX( SUBSTRING_INDEX(@pathall,CONCAT('|',pid,':'),-1),'|',1)

,@pathnodes ) ,pid ) )paths

,@pathall:=CONCAT(@pathall,'|',id,':', @pathnodes ,'|') pathall

FROM treenodes,

(SELECT @le:=0,@pathlevel:='', @pathall:='',@pathnodes:='') vv

ORDER BY pid,id

) src

ORDER BY id

最后的结果如下：

ID   父ID    父到子之间级数  父到子路径

------    ------     --------------------    -------------------

1       0              0                     ,0

2       1              1                     ,0,1

3       1              1                     ,0,1

4       2              2                     ,0,1,2

5       2              2                     ,0,1,2

6       3              2                     ,0,1,3

7       6              3                     ,0,1,3,6

8       0              0                     ,0

9       8              1                     ,0,8

10       8             1                     ,0,8

11       8             1                     ,0,8

12       9             2                     ,0,8,9

13       9             2                     ,0,8,9

14      12            3                      ,0,8,9,12

15      12            3                     ,0,8,9,12

16      15            4                     ,0,8,9,12,15

17      15            4                     ,0,8,9,12,15

18       3            2                      ,0,1,3

19       2            2                      ,0,1,2

20       6            3                      ,0,1,3,6

21       8            1                      ,0,8

以上就是小编介绍关于SQL实现MYSQL递归查询的方法，希望对大家的学习有所帮助，如果还有疑问，请在本文底部留言吧。