利用MySQL存储过程分割字符串

（转）http://tec.5lulu.com/detail/104krn1e6p2w78d77.html

现有一段字符串，如apple,banana,orange,pears,grape，要把它按照逗号(,)分割成：

apple
banana
orange
pears
grape

然后使用where in()方法可以查询。

1、具体函数：

1. # 函数：func_split_TotalLength
2. DELIMITER $$
3. DROP function IF EXISTS `func_split_TotalLength` $$
4. CREATE DEFINER=`root`@`%` FUNCTION `func_split_TotalLength`
5. (f_string varchar(1000),f_delimiter varchar(5)) RETURNS int(11)
6. BEGIN
7. # 计算传入字符串的总length
8. return 1+(length(f_string) - length(replace(f_string,f_delimiter,'')));
9. END$$
10. DELIMITER;

1. # 函数：func_split
2. DELIMITER $$
3. DROP function IF EXISTS `func_split` $$
4. CREATE DEFINER=`root`@`%` FUNCTION `func_split`
5. (f_string varchar(1000),f_delimiter varchar(5),f_order int) RETURNS varchar(255) CHARSET utf8
6. BEGIN
7. # 拆分传入的字符串，返回拆分后的新字符串
8. declare result varchar(255) default '';
9. set result = reverse(substring_index(reverse(substring_index(f_string,f_delimiter,f_order)),f_delimiter,1));
10. return result;
11. END$$
12. DELIMITER;

1. # 存储过程：splitString
2. DELIMITER $$
3. DROP PROCEDURE IF EXISTS `splitString` $$
4. CREATE PROCEDURE `splitString`
5. (IN f_string varchar(1000),IN f_delimiter varchar(5))
6. BEGIN
7. # 拆分结果
8. declare cnt int default 0;
9. declare i int default 0;
10. set cnt = func_split_TotalLength(f_string,f_delimiter);
11. DROP TABLE IF EXISTS `tmp_split`;
12. create temporary table `tmp_split` (`status` varchar(128) not null) DEFAULT CHARSET=utf8;
13. while i < cnt
14. do
15. set i = i + 1;
16. insert into tmp_split(`status`) values (func_split(f_string,f_delimiter,i));
17. end while;
18. END$$
19. DELIMITER;

2、测试是否能成功分割

1. call splitString("apple,banana,orange,pears,grape",",");
2. select * from tmp_split;

运行结果如下，说明分割成功：

mysql> call splitString("apple,banana,orange,pears,grape",",");
select * from tmp_split;
Query OK, 1 row affected

+--------+
| status |
+--------+
| apple  |
| banana |
| orange |
| pears  |
| grape  |
+--------+
5 rows in set

mysql>

3、应用where in()查询

1. # 先传入字符串，分割后保存在临时表tmp_split中
2. call splitString("apple,banana,orange,pears,grape",",");
3. # 将查询的结果作为其他查询的条件来使用
4. select * from fruit where in(select * from tmp_split);