摘要:
下文讲述MySQL数据库中substr字符串分隔函数的用法说明,如下所示;
substr字符串分隔函数功能:
substr系统函数的功能:
对字符串进行分隔,并返回分隔后的字符串
substr字符串分隔函数的四种语法形式:
str:待分隔字符串
pos:起始位置
len:截取长度
substr(str,pos)
从pos开始截取字符串,直到结尾
substr(str,pos,len)
从pos开始截取字符串,
共截取len位
substr(str from pos)
同substr(str,pos)相同
substr(str from pos for len)
同substr(str,pos,len)相同
注意事项:
1.pos值不可以为零,pos为0时,返回空字符串
2.len值小于等于0时,则返回空字符串
3.pos为负数时,则从右边数字符串的开始位置
例:
mysql> select substr('maomao365.com',0);
+---------------------------+
| substr('maomao365.com',0) |
+---------------------------+
| |
+---------------------------+
1 row in set (0.00 sec)
mysql> select substr('maomao365.com',1);
+---------------------------+
| substr('maomao365.com',1) |
+---------------------------+
| maomao365.com |
+---------------------------+
1 row in set (0.00 sec)
mysql> select substr('maomao365.com',2);
+---------------------------+
| substr('maomao365.com',2) |
+---------------------------+
| aomao365.com |
+---------------------------+
1 row in set (0.00 sec)
mysql> select substr('maomao365.com',-1);
+----------------------------+
| substr('maomao365.com',-1) |
+----------------------------+
| m |
+----------------------------+
1 row in set (0.00 sec)
mysql> select substr('maomao365.com',-2);
+----------------------------+
| substr('maomao365.com',-2) |
+----------------------------+
| om |
+----------------------------+
1 row in set (0.00 sec)
mysql> select substr('maomao365.com',-2,10);
+-------------------------------+
| substr('maomao365.com',-2,10) |
+-------------------------------+
| om |
+-------------------------------+
1 row in set (0.00 sec)
mysql> select substr('maomao365.com',2,10);
+------------------------------+
| substr('maomao365.com',2,10) |
+------------------------------+
| aomao365.c |
+------------------------------+
1 row in set (0.00 sec)
mysql> select substr('maomao365.com',0,10);
+------------------------------+
| substr('maomao365.com',0,10) |
+------------------------------+
| |
+------------------------------+
1 row in set (0.00 sec)
mysql> select substr('maomao365.com' from 3);
+--------------------------------+
| substr('maomao365.com' from 3) |
+--------------------------------+
| omao365.com |
+--------------------------------+
1 row in set (0.00 sec)
mysql> select substr('maomao365.com' from 3 for 10);
+---------------------------------------+
| substr('maomao365.com' from 3 for 10) |
+---------------------------------------+
| omao365.co |
+---------------------------------------+
1 row in set (0.00 sec)
mysql> select substr('maomao365.com' from 3 for -1);
+---------------------------------------+
| substr('maomao365.com' from 3 for -1) |
+---------------------------------------+
| |
+---------------------------------------+
1 row in set (0.00 sec)
mysql> select substr('maomao365.com' from 3 for 0);
+--------------------------------------+
| substr('maomao365.com' from 3 for 0) |
+--------------------------------------+
| |
+--------------------------------------+
1 row in set (0.00 sec)
最后
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