mysql sql 字符串函数大全_mysql常用字符串操作函数大全

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测试表

CREATE TABLE `string_test` (

`id` int(11) NOT NULL auto_increment COMMENT ‘用户ID‘,

`name` varchar(50) NOT NULL default ‘‘ COMMENT ‘名称‘,

`job` varchar(23) NOT NULL COMMENT ‘工作‘,

`sex` tinyint(1) NOT NULL default ‘1‘ COMMENT ‘性别‘,

`hobby` varchar(100) character set utf8 collate utf8_unicode_ci default NULL COMMENT ‘爱好‘,

PRIMARY KEY (`id`)

) ENGINE=MyISAM DEFAULT CHARSET=utf8 AUTO_INCREMENT=1 ;

测试数据

INSERT INTO `string_test` (`id`, `name`, `job`, `sex`, `hobby`) VALUES

(1, ‘tank‘, ‘农民工‘, 1, ‘军棋,游戏,fishing‘),

(2, ‘zhang‘, ‘DUCK‘, 0, ‘fly,make firend‘),

(3, ‘ying‘, ‘no job‘, 1, ‘flying,driving,testing‘),

(4, ‘tankzhang‘, ‘love your love‘, 1, ‘i love you‘);

idnamejobsexhobby

tank

农民工

军棋,游戏,fishing

zhang

DUCK

fly,make firend

ying

no job

flying,driving,testing

tankzhang

love your love

i love you

二，mysql字符串操作函数

1，UPPER和UCASE

返回字符串str，根据当前字符集映射(缺省是ISO-8859-1 Latin1)把所有的字符改变成大写。该函数对多字节是可靠的。

mysql> select name,UPPER(name) from string_test where name=‘tank‘;

+------+-------------+

| name | UPPER(name) |

+------+-------------+

| tank | TANK |

+------+-------------+

1 row in set (0.00 sec)

2，LOWER和LCASE

返回字符串str，根据当前字符集映射(缺省是ISO-8859-1 Latin1)把所有的字符改变成小写。该函数对多字节是可靠的。

mysql> select sex,LCASE(job) from string_test where job=‘DUCK‘;

+------+------------+

| sex | LCASE(job) |

+------+------------+

| 1 | duck |

+------+------------+

1 row in set (0.00 sec)

3，FIND_IN_SET(str,strlist)

如果字符串str在由N子串组成的表strlist之中，返回一个1到N的值。一个字符串表是被“,”分隔的子串组成的一个字符串。如果第一个参数是一个常数字符串并且第二个参数是一种类型为SET的列，FIND_IN_SET()函数被优化而使用位运算！如果str不是在strlist里面或如果strlist是空字符串，返回0。如果任何一个参数是NULL，返回NULL。如果第一个参数包含一个“,”，该函数将工作不正常。看面是二种不同的效果，可以看一下

mysql> SELECT id,name FROM string_test WHERE find_in_set(‘fly‘,hobby);

+----+-------+

| id | name |

+----+-------+

| 2 | zhang |

+----+-------+

1 row in set (0.00 sec)

mysql> SELECT id,name FROM string_test WHERE hobby like ‘fly%‘;

+----+-------+

| id | name |

+----+-------+

| 2 | zhang |

| 3 | ying |

+----+-------+

2 rows in set (0.00 sec)

4，FIELD(str,str1,str2,str3,...)

返回str在str1, str2, str3, ...清单的索引。如果str没找到，返回0。FIELD()是ELT()反运算。

mysql> SELECT id, name, FIELD( id, name, sex, job, hobby )

-> FROM string_test where id < 4;

+----+-------+------------------------------------+

| id | name | FIELD( id, name, sex, job, hobby ) |

+----+-------+------------------------------------+

| 1 | tank | 2 |

| 2 | zhang | 0 |

| 3 | ying | 0 |

+----+-------+------------------------------------+

3 rows in set (0.00 sec)

5.ELT(N,str1,str2,str3,...)

如果N= 1，返回str1，如果N= 2，返回str2，等等。如果N小于1或大于参数个数，返回NULL。ELT()是FIELD()反运算。

mysql> SELECT id, name, ELT(1, id, name, sex, job, hobby ) FROM string_test where id < 4;

+----+-------+------------------------------------+

| id | name | ELT(1, id, name, sex, job, hobby ) |

+----+-------+------------------------------------+

| 1 | tank | 1 |

| 2 | zhang | 2 |

| 3 | ying | 3 |

+----+-------+------------------------------------+

3 rows in set (0.00 sec)

mysql> SELECT id, name, ELT(2, id, name, sex, job, hobby ) FROM string_test where id < 4;

+----+-------+------------------------------------+

| id | name | ELT(2, id, name, sex, job, hobby ) |

+----+-------+------------------------------------+

| 1 | tank | tank |

| 2 | zhang | zhang |

| 3 | ying | ying |

+----+-------+------------------------------------+

3 rows in set (0.00 sec)

6，REPLACE(str,from_str,to_str)

返回字符串str，其字符串from_str的所有出现由字符串to_str代替。

mysql> SELECT id,REPLACE(hobby,"firend",‘living‘) FROM string_test WHERE id = 2;

+----+----------------------------------+

| id | REPLACE(hobby,"firend",‘living‘) |

+----+----------------------------------+

| 2 | fly,make living |

+----+----------------------------------+

1 row in set (0.00 sec)

7，REPEAT(str,count)

返回由重复countTimes次的字符串str组成的一个字符串。如果count <= 0，返回一个空字符串。如果str或count是NULL，返回NULL。

mysql> SELECT id,REPEAT(name,2) FROM string_test WHERE id > 1 and id < 4;

+----+----------------+

| id | REPEAT(name,2) |

+----+----------------+

| 2 | zhangzhang |

| 3 | yingying |

+----+----------------+

2 rows in set (0.00 sec)

8，REVERSE(str)

返回颠倒字符顺序的字符串str。

mysql> SELECT id,reverse(name) FROM string_test WHERE id > 1 and id < 4;

+----+---------------+

| id | reverse(name) |

+----+---------------+

| 2 | gnahz |

| 3 | gniy |

+----+---------------+

2 rows in set (0.00 sec)

9，INSERT(str,pos,len,newstr)

返回字符串str，在位置pos起始的子串且len个字符长得子串由字符串newstr代替。

mysql> select id,name,INSERT(hobby,10,6,‘living‘) from string_test where id = 2;

+----+-------+-----------------------------+

| id | name | INSERT(hobby,10,6,‘living‘) |

+----+-------+-----------------------------+

| 2 | zhang | fly,make living |

+----+-------+-----------------------------+

1 row in set (0.00 sec)

10，SUBSTRING(str FROM pos)

从字符串str的起始位置pos返回一个子串。下面的sub2没有值，因为mysql数据库的下标是从1开始的。

mysql> SELECT id, substring( hobby, 1, 6) AS sub1, substring( hobby from 0 for 8

) AS sub2,substring( hobby,2) AS sub3, substring( hobby from 4 ) AS sub4 FROM s

tring_test WHERE id =4;

+----+--------+------+-----------+---------+

| id | sub1 | sub2 | sub3 | sub4 |

+----+--------+------+-----------+---------+

+----+--------+------+-----------+---------+

1 row in set (0.00 sec)

11,SUBSTRING_INDEX(str,delim,count)

返回从字符串str的第count个出现的分隔符delim之后的子串。如果count是正数，返回最后的分隔符到左边(从左边数) 的所有字符。如果count是负数，返回最后的分隔符到右边的所有字符(从右边数)。

mysql> SELECT id,SUBSTRING_INDEX(hobby,‘,‘,2) as test1,SUBSTRING_INDEX(hobby,‘,‘

,-1) as test2 FROM string_test WHERE id = 3;

+----+----------------+---------+

| id | test1 | test2 |

+----+----------------+---------+

| 3 | flying,driving | testing |

+----+----------------+---------+

1 row in set (0.01 sec)

12,LTRIM(str)

返回删除了其前置空格字符的字符串str。

mysql> SELECT id,LTRIM(job) FROM string_test WHERE id = 4;

+----+----------------+

| id | LTRIM(job) |

+----+----------------+

| 4 | love your love |

+----+----------------+

1 row in set (0.00 sec)

13,RTRIM(str)

返回删除了其拖后空格字符的字符串str。

mysql> SELECT id,RTRIM(job) FROM string_test WHERE id = 4;

+----+----------------+

| id | RTRIM(job) |

+----+----------------+

| 4 | love your love |

+----+----------------+

1 row in set (0.00 sec)

14,TRIM([[BOTH | LEADING | TRAILING] [remstr] FROM] str)

返回字符串str，其所有remstr前缀或后缀被删除了。如果没有修饰符BOTH、LEADING或TRAILING给出，BOTH被假定。如果remstr没被指定，空格被删除。

mysql> select trim(‘ test ‘);

+-----------------+

| trim(‘ test ‘) |

+-----------------+

| test |

+-----------------+

1 row in set (0.01 sec)

mysql> SELECT id,TRIM(LEADING "love" from job) as test1,TRIM(BOTH "love" from jo

b) as test2,TRIM(TRAILING "love" from job) as test3 FROM string_test WHERE id =

-> ;

+----+------------+--------+------------+

+----+------------+--------+------------+

+----+------------+--------+------------+

1 row in set (0.00 sec)

15,MID(str,pos,len)

从字符串str返回一个len个字符的子串，从位置pos开始。使用FROM的变种形式是ANSI SQL92语法。

mysql> SELECT id, mid( hobby, 1, 6 ) AS sub1, mid( hobby

-> FROM 0

-> FOR 8 ) AS sub2, mid( hobby, 2 ) AS sub3, mid( hobby

-> FROM 4 ) AS sub4

-> FROM string_test

-> WHERE id =4 ;

+----+--------+------+-----------+---------+

| id | sub1 | sub2 | sub3 | sub4 |

+----+--------+------+-----------+---------+

+----+--------+------+-----------+---------+

1 row in set (0.00 sec)

mysql>

16，LPAD(str,len,padstr)

返回字符串str，左面用字符串padstr填补直到str是len个字符长。

mysql> SELECT id,LPAD(name,11,"zhang ") FROM string_test WHERE id = 3;

+----+------------------------+

| id | LPAD(name,11,"zhang ") |

+----+------------------------+

| 3 | zhang zying |

+----+------------------------+

1 row in set (0.00 sec)

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17,RPAD(str,len,padstr)

返回字符串str，右面用字符串padstr填补直到str是len个字符长。

mysql> SELECT id,RPAD(name,11," ying") FROM string_test WHERE id = 2;

+----+-----------------------+

| id | RPAD(name,11," ying") |

+----+-----------------------+

| 2 | zhang ying |

+----+-----------------------+

1 row in set (0.00 sec)

18,LEFT(str,len)

返回字符串str的最左面len个字符。

mysql> SELECT id,left(job,4) FROM string_test WHERE id = 4;

+----+-------------+

| id | left(job,4) |

+----+-------------+

| 4 | love |

+----+-------------+

1 row in set (0.00 sec)

19,RIGHT(str,len)

返回字符串str的最右面len个字符。

mysql> SELECT id,right(job,4) FROM string_test WHERE id = 4;

+----+--------------+

| id | right(job,4) |

+----+--------------+

| 4 | love |

+----+--------------+

1 row in set (0.00 sec)

20,位置控制函数

POSITION(substr IN str)

返回子串substr在字符串str第一个出现的位置，如果substr不是在str里面，返回0.

LOCATE(substr,str,pos)

返回子串substr在字符串str第一个出现的位置，从位置pos开始。如果substr不是在str里面，返回0。

INSTR(str,substr)

返回子串substr在字符串str中的第一个出现的位置。这与有2个参数形式的LOCATE()相同，除了参数被颠倒。

mysql> SELECT id,INSTR(job,"you") as instr,LOCATE(‘love‘,job,3) as locate,POSITI

ON(‘love‘ in job) as position FROM string_test WHERE id = 4;

+----+-------+--------+----------+

+----+-------+--------+----------+

| 4 | 6 | 11 | 1 |

+----+-------+--------+----------+

1 row in set (0.00 sec)

21，得到字符串长度的函数

LENGTH(str),OCTET_LENGTH(str),CHAR_LENGTH(str),CHARACTER_LENGTH(str)

mysql> SELECT id,LENGTH(job) as one,OCTET_LENGTH(job) as two,CHAR_LENGTH(job) as

three,CHARACTER_LENGTH(job) as four FROM string_test WHERE id = 4;

+----+-----+-----+-------+------+

| id | one | two | three | four |

+----+-----+-----+-------+------+

| 4 | 14 | 14 | 14 | 14 |

+----+-----+-----+-------+------+

1 row in set (0.00 sec)

22，合并多个字符串，或者表中的多个字段

CONCAT(str1,str2,...)

返回来自于参数连结的字符串。如果任何参数是NULL，返回NULL。可以有超过2个的参数。一个数字参数被变换为等价的字符串形式。

mysql> SELECT id,CONCAT(name,job,hobby) FROM string_test WHERE id = 4;

+----+-----------------------------------+

| id | CONCAT(name,job,hobby) |

+----+-----------------------------------+

| 4 | tankzhanglove your lovei love you |

+----+-----------------------------------+

1 row in set (0.00 sec)

23，进制转换

BIN(N)

返回二进制值N的一个字符串表示，在此N是一个长整数(BIGINT)数字，这等价于CONV(N,10,2)。如果N是NULL，返回NULL。

OCT(N)

返回八进制值N的一个字符串的表示，在此N是一个长整型数字，这等价于CONV(N,10,8)。如果N是NULL，返回NULL。

HEX(N)

返回十六进制值N一个字符串的表示，在此N是一个长整型(BIGINT)数字，这等价于CONV(N,10,16)。如果N是NULL，返回NULL。

ASCII(str)

返回字符串str的最左面字符的ASCII代码值。如果str是空字符串，返回0。如果str是NULL，返回NULL。

mysql> select bin(20),oct(20),hex(20),ascii(20);

+---------+---------+---------+-----------+

| bin(20) | oct(20) | hex(20) | ascii(20) |

+---------+---------+---------+-----------+

| 10100 | 24 | 14 | 50 |

+---------+---------+---------+-----------+

1 row in set (0.02 sec)

MySQL 字符串大小写转化函数有两对： lower(), uppper() 和 lcase(), ucase()

mysql> select lower(‘DDD‘);

+--------------+

| lower(‘DDD‘) |

+--------------+

| ddd |

+--------------+

mysql> select upper(‘ddd‘);

+--------------+

| upper(‘ddd‘) |

+--------------+

| DDD |

+--------------+

mysql> select lcase(‘DDD‘);

+--------------+

| lcase(‘DDD‘) |

+--------------+

| ddd |

+--------------+

mysql> select ucase(‘ddd‘);

+--------------+

| ucase(‘ddd‘) |

+--------------+

| DDD |

+--------------+

通常情况下，我选择 lower(), upper() 来转换字符串大小写，因为这和其他数据库中函数相兼容。

清除字符串首尾空格

MySQL 中的清除字符串首尾空格函数有三个： ltrim(), rtrim(), trim()

mysql> select concat(‘.‘, ltrim(‘ ddd ‘), ‘.‘);

+----------------------------------+

| concat(‘.‘, ltrim(‘ ddd ‘), ‘.‘) |

+----------------------------------+

| .ddd . |

+----------------------------------+

mysql> select concat(‘.‘, rtrim(‘ ddd ‘), ‘.‘);

+----------------------------------+

| concat(‘.‘, rtrim(‘ ddd ‘), ‘.‘) |

+----------------------------------+

| . ddd. |

+----------------------------------+

mysql> select concat(‘.‘, trim(‘ ddd ‘), ‘.‘);

+---------------------------------+

| concat(‘.‘, trim(‘ ddd ‘), ‘.‘) |

+---------------------------------+

| .ddd. |

+---------------------------------+

MySQL 中的 trim 字符串函数，实在是强大。它不仅能消除字符串首尾部的空格，还可以消除我们指定的任意字符。ltrim(), rtrim() 只是它的一个功能子集。来看下 trim 函数的完整语法：

1. trim([{both | leading | trailing} [remstr] from] str)

2. trim([remstr from] str)

1. 清除字符串首部字符。

mysql> select trim(leading ‘.‘ from ‘..ddd..‘);

+----------------------------------+

| trim(leading ‘.‘ from ‘..ddd..‘) |

+----------------------------------+

| ddd.. |

+----------------------------------+

2. 清除字符串尾部字符。

mysql> select trim(trailing ‘.‘ from ‘..ddd..‘);

+-----------------------------------+

| trim(trailing ‘.‘ from ‘..ddd..‘) |

+-----------------------------------+

| ..ddd |

+-----------------------------------+

3. 清除字符串首尾部字符。

mysql> select trim(both ‘.‘ from ‘..ddd..‘);

+-------------------------------+

| trim(both ‘.‘ from ‘..ddd..‘) |

+-------------------------------+

| ddd |

+-------------------------------+

mysql> select trim(‘.‘ from ‘..ddd..‘);

+--------------------------+

| trim(‘.‘ from ‘..ddd..‘) |

+--------------------------+

| ddd |

+--------------------------+

trim() 默认清除字符串首尾部的空格。

字符串截取

MySQL 字符串截取函数：left(), right(), substring(), substring_index()。还有 mid(), substr()。其中，mid(), substr() 等价于 substring() 函数，substring() 的功能非常强大和灵活。

1. 字符串截取：left(str, length)

mysql> select left(‘sqlstudy.com‘, 3);

+-------------------------+

| left(‘sqlstudy.com‘, 3) |

+-------------------------+

| sql |

+-------------------------+

2. 字符串截取：right(str, length)

mysql> select right(‘sqlstudy.com‘, 3);

+--------------------------+

| right(‘sqlstudy.com‘, 3) |

+--------------------------+

| com |

+--------------------------+

3. 字符串截取：substring(str, pos); substring(str, pos, len)

3.1 从字符串的第 4 个字符位置开始取，直到结束。

mysql> select substring(‘sqlstudy.com‘, 4);

+------------------------------+

| substring(‘sqlstudy.com‘, 4) |

+------------------------------+

| study.com |

+------------------------------+

3.2 从字符串的第 4 个字符位置开始取，只取 2 个字符。

mysql> select substring(‘sqlstudy.com‘, 4, 2);

+---------------------------------+

| substring(‘sqlstudy.com‘, 4, 2) |

+---------------------------------+

| st |

+---------------------------------+

3.3 从字符串的第 4 个字符位置(倒数)开始取，直到结束。

mysql> select substring(‘sqlstudy.com‘, -4);

+-------------------------------+

| substring(‘sqlstudy.com‘, -4) |

+-------------------------------+

| .com |

+-------------------------------+

3.4 从字符串的第 4 个字符位置(倒数)开始取，只取 2 个字符。

mysql> select substring(‘sqlstudy.com‘, -4, 2);

+----------------------------------+

| substring(‘sqlstudy.com‘, -4, 2) |

+----------------------------------+

| .c |

+----------------------------------+

我们注意到在函数 substring(str,pos, len)中， pos 可以是负值，但 len 不能取负值。

4. 字符串截取：substring_index(str,delim,count)

4.1 截取第二个 ‘.‘ 之前的所有字符。

mysql> select substring_index(‘www.sqlstudy.com.cn‘, ‘.‘, 2);

+------------------------------------------------+

| substring_index(‘www.sqlstudy.com.cn‘, ‘.‘, 2) |

+------------------------------------------------+

| www.sqlstudy |

+------------------------------------------------+

4.2 截取第二个 ‘.‘ (倒数)之后的所有字符。

mysql> select substring_index(‘www.sqlstudy.com.cn‘, ‘.‘, -2);

+-------------------------------------------------+

| substring_index(‘www.sqlstudy.com.cn‘, ‘.‘, -2) |

+-------------------------------------------------+

| com.cn |

+-------------------------------------------------+

4.3 如果在字符串中找不到 delim 参数指定的值，就返回整个字符串

mysql> select substring_index(‘www.sqlstudy.com.cn‘, ‘.coc‘, 1);

+---------------------------------------------------+

| substring_index(‘www.sqlstudy.com.cn‘, ‘.coc‘, 1) |

+---------------------------------------------------+

| www.sqlstudy.com.cn |

+---------------------------------------------------+

原文：http://www.cnblogs.com/aprils/p/3983407.html

mysql sql 字符串函数大全_mysql常用字符串操作函数大全

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