MySQL常用函数汇总——字符串操作函数

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  1. LENGTH 计算字符串长度函数,返回字符串的字节长度
    mysql> SELECT LENGTH(name),LENGTH(数据库);
    +----------------+---------------------+
    |LENGTH(name)  | LENGTH(数据库)    |
    +----------------+---------------------+
    |              4 |                   9 |
    +----------------+---------------------+
    1 row in set (0.04 sec)

     

  2. CONCAT 合并字符串函数,返回结果为连接参数产生的字符串,可以有多个参数
    mysql> SELECT CONCAT(MySQL,5.7),CONCAT(MySQL,NULL);
    +-----------------------+----------------------+
    | CONCAT(MySQL,5.7) | CONCAT(MySQL,NULL) |
    +-----------------------+----------------------+
    | MySQL5.7              | NULL                 |
    +-----------------------+----------------------+
    1 row in set (0.03 sec)

     

  3. INSERT 替换字符串
    mysql> SELECT INSERT(Football,2,4,Play) AS col1,
        -> INSERT(Football,-1,4,Play) AS col2,
        -> INSERT(Football,3,20,Play) AS col3;
    +----------+----------+--------+
    | col1     | col2     | col3   |
    +----------+----------+--------+
    | FPlayall | Football | FoPlay |
    +----------+----------+--------+
    1 row in set (0.04 sec)

     

  4. LOWER 字母转换为小写
    mysql> SELECT LOWER(BLUE),LOWER(Blue);
    +---------------+---------------+
    | LOWER(BLUE) | LOWER(Blue) |
    +---------------+---------------+
    | blue          | blue          |
    +---------------+---------------+
    1 row in set (0.03 sec)

     

  5. UPPER 字母转换为大写
    mysql> SELECT UPPER(green),UPPER(Green);
    +----------------+----------------+
    | UPPER(green) | UPPER(Green) |
    +----------------+----------------+
    | GREEN          | GREEN          |
    +----------------+----------------+
    1 row in set (0.03 sec)

     

  6. LEFT 从左侧字截取符串,返回字符串左边的若干个字符
    mysql> SELECT LEFT(MySQL,2);
    +-----------------+
    | LEFT(MySQL,2) |
    +-----------------+
    | My              |
    +-----------------+
    1 row in set (0.04 sec)

     

  7. RIGHT 从右侧字截取符串,返回字符串右边的若干个字符
    mysql> SELECT RIGHT(MySQL,3);
    +------------------+
    | RIGHT(MySQL,3) |
    +------------------+
    | SQL              |
    +------------------+
    1 row in set (0.00 sec)

     

  8. TRIM 删除字符串左右两侧的空格
    mysql> SELECT [   mobile   ],CONCAT([,TRIM(   mobile   ),]);
    +----------------+--------------------------------------+
    | [   mobile   ] | CONCAT([,TRIM(   mobile   ),]) |
    +----------------+--------------------------------------+
    | [   mobile   ] | [mobile]                             |
    +----------------+--------------------------------------+
    1 row in set (0.07 sec)

     

  9. REPLACE 替换字符串
    mysql> SELECT REPLACE(aaa.mysql.com,a,w);
    +----------------------------------+
    | REPLACE(aaa.mysql.com,a,w) |
    +----------------------------------+
    | www.mysql.com                    |
    +----------------------------------+
    1 row in set (0.00 sec)

     

  10. SUBSTRING 截取字符串
    mysql> SELECT SUBSTRING(computer,3) AS col1,
        -> SUBSTRING(computer,3,4) AS col2,
        -> SUBSTRING(computer,-3) AS col3,
        -> SUBSTRING(computer,-5,3) AS col4;
    +--------+------+------+------+
    | col1   | col2 | col3 | col4 |
    +--------+------+------+------+
    | mputer | mput | ter  | put  |
    +--------+------+------+------+
    1 row in set (0.00 sec)

     

  11. REVERSE 反转字符串
    mysql> SELECT REVERSE(hello);
    +------------------+
    | REVERSE(hello) |
    +------------------+
    | olleh            |
    +------------------+
    1 row in set (0.00 sec)

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