mysql函数以及递归sql

最新推荐文章于 2025-07-15 14:47:11 发布

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最新推荐文章于 2025-07-15 14:47:11 发布

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---查看创建函数的功能是否开启：
show variables like '%func%';
set global log_bin_trust_function_creators=1;

------delimiter命令终止符号将;改为//
delimiter //
mysql> CREATE FUNCTION first_func(param1 varchar(5),parmam2 varchar(5),param3 varchar(10))
    -> RETURNS TINYINT
    -> BEGIN
    -> RETURN 1;
    -> END
    -> //
Query OK, 0 rows affected

----------将终止符改回为;
mysql> delimiter ;

--删除函数：
drop function first_func ;
--查看函数
show function status
----查看某个具体函数
show create function first_func;

转载：http://blog.youkuaiyun.com/ACMAIN_CHM/article/details/4142971

样例数据：

mysql> create table treeNodes
    -> (
    -> id int primary key,
    -> nodename varchar(20),
    -> pid int
    -> );
Query OK, 0 rows affected (0.09 sec)
mysql> select * from treenodes;
+----+----------+------+
| id | nodename | pid |
+----+----------+------+
| 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 |
+----+----------+------+
17 rows in set (0.00 sec)

树形图如下

1:A
+-- 2:B
|    +-- 4:D
|    +-- 5:E
+-- 3:C
       +-- 6:F
            +-- 7:G
8:H
+-- 9:I
|    +-- 12:L
|    |    +--14:N
|    |    +--15:O
|    |        +--16:P
|    |        +--17:Q
|    +-- 13:M
+-- 10:J
+-- 11:K

方法一：利用函数来得到所有子节点号。

创建一个function getChildLst, 得到一个由所有子节点号组成的字符串.

mysql> delimiter //
mysql>
mysql> CREATE FUNCTION `getChildLst`(rootId INT)
-> RETURNS varchar(1000)
-> BEGIN
-> DECLARE sTemp VARCHAR(1000);
-> DECLARE sTempChd VARCHAR(1000);
->
-> SET sTemp = '$';
-> SET sTempChd =cast(rootId as CHAR);
->
-> WHILE sTempChd is not null DO
-> SET sTemp = concat(sTemp,',',sTempChd);
-> SELECT group_concat(id) INTO sTempChd FROM treeNodes where FIND_IN_SET(pid,sTempChd)>0;
-> END WHILE;
-> RETURN sTemp;
-> END
-> //
Query OK, 0 rows affected (0.00 sec)

mysql>
mysql> delimiter ;

使用我们直接利用find_in_set函数配合这个getChildlst来查找

mysql> select getChildLst(1);
+-----------------+
| getChildLst(1)  |
+-----------------+
| $,1,2,3,4,5,6,7 |
+-----------------+
1 row in set (0.00 sec)

mysql> select * from treeNodes
-> where FIND_IN_SET(id, getChildLst(1));
+----+----------+------+
| id | nodename | pid  |
+----+----------+------+
|  1 | A       | 0 |
|  2 | B       | 1 |
|  3 | C       | 1 |
|  4 | D       | 2 |
|  5 | E       | 2 |
|  6 | F       | 3 |
|  7 | G       | 6 |
+----+----------+------+
7 rows in set (0.01 sec)

mysql> select * from treeNodes
-> where FIND_IN_SET(id, getChildLst(3));
+----+----------+------+
| id | nodename | pid  |
+----+----------+------+
|  3 | C       | 1 |
|  6 | F       | 3 |
|  7 | G       | 6 |
+----+----------+------+
3 rows in set (0.01 sec)

优点: 简单，方便，没有递归调用层次深度的限制 (max_sp_recursion_depth,最大255) ；

缺点：长度受限，虽然可以扩大 RETURNS varchar(1000)，但总是有最大限制的。

MySQL目前版本( 5.1.33-community)中还不支持function 的递归调用。

方法二：利用临时表和过程递归

创建存储过程如下。createChildLst 为递归过程，showChildLst为调用入口过程，准备临时表及初始化。

mysql> delimiter //
mysql>
mysql> # 入口过程
mysql> CREATE PROCEDURE showChildLst (IN rootId INT)
-> BEGIN
    -> CREATE TEMPORARY TABLE IF NOT EXISTS tmpLst
    -> (sno int primary key auto_increment,id int,depth int);
->  DELETE FROM tmpLst;
->
->  CALL createChildLst(rootId,0);
->
->  select tmpLst.*,treeNodes.* from tmpLst,treeNodes where tmpLst.id=treeNodes.id order by tmpLst.sno;
-> END;
-> //
Query OK, 0 rows affected (0.00 sec)

mysql>
mysql> # 递归过程
mysql> CREATE PROCEDURE createChildLst (IN rootId INT,IN nDepth INT)
-> BEGIN
->  DECLARE done INT DEFAULT 0;
->  DECLARE b INT;
->  DECLARE cur1 CURSOR FOR SELECT id FROM treeNodes where pid=rootId;
->  DECLARE CONTINUE HANDLER FOR NOT FOUND SET done = 1;
->
->  insert into tmpLst values (null,rootId,nDepth);

    ->
->  OPEN cur1;
->
->  FETCH cur1 INTO b;
->  WHILE done=0 DO
->       CALL createChildLst(b,nDepth+1);
->       FETCH cur1 INTO b;
->  END WHILE;
->
->  CLOSE cur1;
-> END;
-> //
Query OK, 0 rows affected (0.00 sec)
mysql> delimiter ;

调用时传入结点

mysql> call showChildLst(1);
+-----+------+-------+----+----------+------+
| sno | id   | depth | id | nodename | pid |
+-----+------+-------+----+----------+------+
|   4 |    1 |     0 | 1 | A        |    0 |
|   5 |    2 |     1 | 2 | B        |    1 |
|   6 |    4 |     2 | 4 | D        |    2 |
|   7 |    5 |     2 | 5 | E        |    2 |
|   8 |    3 |     1 | 3 | C        |    1 |
|   9 |    6 |     2 | 6 | F        |    3 |
| 10 |    7 |     3 | 7 | G        |    6 |
+-----+------+-------+----+----------+------+

7 rows in set (0.13 sec)

Query OK, 0 rows affected, 1 warning (0.14 sec)

mysql>
mysql> call showChildLst(3);
+-----+------+-------+----+----------+------+
| sno | id   | depth | id | nodename | pid |
+-----+------+-------+----+----------+------+
|   1 |    3 |     0 | 3 | C        |    1 |
|   2 |    6 |     1 | 6 | F        |    3 |
|   3 |    7 |     2 | 7 | G        |    6 |
+-----+------+-------+----+----------+------+

3 rows in set (0.11 sec)

Query OK, 0 rows affected, 1 warning (0.11 sec)

depth 为深度，这样可以在程序进行一些显示上的格式化处理。类似于oracle中的 level 伪列。sno 仅供排序控制。这样你还可以通过临时表tmpLst与数据库中其它表进行联接查询。

MySQL中你可以利用系统参数 max_sp_recursion_depth 来控制递归调用的层数上限。如下例设为12.

mysql> set max_sp_recursion_depth=12;
Query OK, 0 rows affected (0.00 sec)

优点 : 可以更灵活处理，及层数的显示。并且可以按照树的遍历顺序得到结果。

缺点 : 递归有255的限制。

方法三：利用中间表和过程

(本方法由yongyupost2000提供样子改编)

创建存储过程如下。由于MySQL中不允许在同一语句中对临时表多次引用，只以使用普通表tmpLst来实现了。当然你的程序中负责在用完后清除这个表。

delimiter //

drop PROCEDURE IF EXISTS showTreeNodes_yongyupost2000//

CREATE PROCEDURE showTreeNodes_yongyupost2000 (IN rootid INT)
BEGIN
DECLARE Level int ;
drop TABLE IF EXISTS tmpLst;
CREATE TABLE tmpLst (
  id int,
  nLevel int,
  sCort varchar(8000)
);

Set Level=0 ;
INSERT into tmpLst SELECT id,Level,ID FROM treeNodes WHERE PID=rootid;
WHILE ROW_COUNT()>0 DO
  SET Level=Level+1 ;
  INSERT into tmpLst
   SELECT A.ID,Level,concat(B.sCort,A.ID) FROM treeNodes A,tmpLst B
    WHERE A.PID=B.ID AND B.nLevel=Level-1 ;
END WHILE;

END;
//

delimiter ;

CALL showTreeNodes_yongyupost2000(0);

执行完后会产生一个tmpLst表，nLevel 为节点深度，sCort 为排序字段。
使用方法

SELECT concat(SPACE(B.nLevel*2),'+--',A.nodename)
FROM treeNodes A,tmpLst B
WHERE A.ID=B.ID
ORDER BY B.sCort;

+--------------------------------------------+
| concat(SPACE(B.nLevel*2),'+--',A.nodename) |
+--------------------------------------------+
| +--A                                       |
|   +--B                                     |
|     +--D                                   |
|     +--E                                   |
|   +--C                                     |
|     +--F                                   |
|       +--G                                 |
| +--H                                       |
|   +--J                                     |
|   +--K                                     |
|   +--I                                     |
|     +--L                                   |
|       +--N                                 |
|       +--O                                 |
|         +--P                               |
|         +--Q                               |
|     +--M                                   |
+--------------------------------------------+
17 rows in set (0.00 sec)