mysql字符串函数3

1.删除制定字符串的函数TRIM(s1 FROM s)

TRIM(s1 FROM s)删除字符串两端所有的子字符串s1。s1为可选项，在未指定情况下，删除空格。

mysql> select trim('xy' from 'xyxboxyokxxyxy');
+----------------------------------+
| trim('xy' from 'xyxboxyokxxyxy') |
+----------------------------------+
| xboxyokx                         |
+----------------------------------+
1 row in set (0.00 sec)

2.重复生成字符串函数REPEAT(s,n)

返回一个由重复的字符串s组成的字符串，字符串的数目等于n，若n<=0返回一个空字符串，若s或n为NULL，则返回NULL

mysql> select repeat('MySQL', 3);
+--------------------+
| repeat('MySQL', 3) |
+--------------------+
| MySQLMySQLMySQL    |
+--------------------+
1 row in set (0.00 sec)

3.空格函数SPACE(n)和替换函数REPLACE(s,s1,s2)

SPACE(n)返回一个由n个空格组成的字符串

mysql> select concat('(', space(6),')');
+---------------------------+
| concat('(', space(6),')') |
+---------------------------+
| (      )                  |
+---------------------------+
1 row in set (0.00 sec)

REPLACE(s,s1,s2)使用字符串s2替代字符串s中所有的字符串s1。

mysql> select replace('xxx.mysql.com','x','w');
+----------------------------------+
| replace('xxx.mysql.com','x','w') |
+----------------------------------+
| www.mysql.com                    |
+----------------------------------+
1 row in set (0.00 sec)