怎样实现对字段使用函数查询

[xchunyu]

例如用select 语句查询满足以下条件的记录：

某字符串类型字段以某个字符开头，即对字段应用substr函数＝某个值
select * from 表1 where substr(字段1,0,2)='02'
另外我想知道php+mysql是否支持like语句模糊查询，如果是，怎样具体实现？

[lierq]

select * from a where left(filed1,4)='".substr(string,0,4)."'"
或
select * from a where filed1 like '".substr(string,0,4)."%'"

[shuixin13]

SELECT Host,User FROM mysql.user WHERE User Like 'root';

SELECT Host,User FROM mysql.user WHERE User Like 'r%';

SELECT Host,User FROM mysql.user WHERE User Like '\%';

SELECT Host,User,SubString(User,1,1) FROM mysql.user WHERE SubString(User,1,1)='r';

[shuixin13]

D:\mysql\bin>mysql
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 4 to server version: 3.23.43-nt-log

Type 'help;' or '\h' for help. Type '\c' to clear the buffer.

mysql> SELECT Host,User FROM mysql.user;
+-----------+-------+
| Host | User |
+-----------+-------+
| % | root |
| localhost | |
| localhost | Guest |
| localhost | card |
| localhost | root |
| pc02 | root |
+-----------+-------+
6 rows in set (0.00 sec)
->查看mysql.user所有数据

mysql> SELECT Host,User FROM mysql.user WHERE User Like 'root';
+-----------+------+
| Host | User |
+-----------+------+
| % | root |
| localhost | root |
| pc02 | root |
+-----------+------+
3 rows in set (0.01 sec)
->等同于SELECT Host,User FROM mysql.user WHERE User = 'root';

mysql> SELECT Host,User FROM mysql.user WHERE User Like 'r%';
+-----------+------+
| Host | User |
+-----------+------+
| % | root |
| localhost | root |
| pc02 | root |
+-----------+------+
3 rows in set (0.00 sec)
->查看所有User第一个字符为 'r' 的

mysql> SELECT Host,User FROM mysql.user WHERE Host Like '\%';
+------+------+
| Host | User |
+------+------+
| % | root |
+------+------+
1 row in set (0.00 sec)
->查看Host 为 '%'的,
\ 表转义

mysql> SELECT Host,User,SubString(User,1,1) FROM mysql.user WHERE SubString(User,1,1)='r';
+-----------+------+---------------------+
| Host | User | SubString(User,1,1) |
+-----------+------+---------------------+
| % | root | r |
| localhost | root | r |
| pc02 | root | r |
+-----------+------+---------------------+
3 rows in set (0.00 sec)
->查看所有User第一个字符为 'r' 的
等同于SELECT Host,User FROM mysql.user WHERE User Like 'r%';

[shuixin13]

D:\mysql\bin>mysql
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 4 to server version: 3.23.43-nt-log

Type 'help;' or '\h' for help. Type '\c' to clear the buffer.

mysql>
mysql>
mysql>
mysql> SELECT Host,User FROM mysql.user;
+-----------+-------+
| Host | User |
+-----------+-------+
| % | root |
| localhost | |
| localhost | Guest |
| localhost | card |
| localhost | root |
| pc02 | root |
+-----------+-------+
6 rows in set (0.00 sec)
->查看mysql.user所有记录

mysql> SELECT Host,User FROM mysql.user WHERE User Like 'root';
+-----------+------+
| Host | User |
+-----------+------+
| % | root |
| localhost | root |
| pc02 | root |
+-----------+------+
3 rows in set (0.01 sec)
->等同于SELECT Host,User FROM mysql.user WHERE User = 'root';

mysql> SELECT Host,User FROM mysql.user WHERE User Like 'r%';
+-----------+------+
| Host | User |
+-----------+------+
| % | root |
| localhost | root |
| pc02 | root |
+-----------+------+
3 rows in set (0.00 sec)
->查看User的第一个字符为 'r'的记录

mysql> SELECT Host,User FROM mysql.user WHERE Host Like '\%';
+------+------+
| Host | User |
+------+------+
| % | root |
+------+------+
1 row in set (0.00 sec)
->查看Host为 '%' 的记录
\ 为转义符

mysql> SELECT Host,User,SubString(User,1,1) FROM mysql.user WHERE SubString(Usr,1,1)='r';
+-----------+------+---------------------+
| Host | User | SubString(User,1,1) |
+-----------+------+---------------------+
| % | root | r |
| localhost | root | r |
| pc02 | root | r |
+-----------+------+---------------------+
3 rows in set (0.00 sec)
->查看User的第一个字符为 'r'的记录
等同于SELECT Host,User FROM mysql.user WHERE User Like 'r%';