正则表达式用于匹配特殊的字符集合。mysql通过where子句对正则表达式提供初步的支持。
关键字regexp用来表示后面跟的东西作为正则表达式处理。
（.）是正则表达式的一个符号，表示匹配任意一个字符：
mysql> select prod_name -> from products -> where prod_name regexp '.000' -> order by prod_name;+--------------+| prod_name |+--------------+| JetPack 1000 || JetPack 2000 |+--------------+2 rows in set (0.14 sec)
|匹配符：
表示匹配其中之一
mysql> select prod_name -> from products -> where prod_name REGEXP '1000|2000' -> ORDER BY prod_name;+--------------+| prod_name |+--------------+| JetPack 1000 || JetPack 2000 |+--------------+2 rows in set (0.00 sec)
[]匹配符： 匹配几个字符之一
2 rows in set (0.00 sec)mysql> select prod_name -> from products -> where prod_name regexp '[123] Ton' -> ;+-------------+| prod_name |+-------------+| 1 ton anvil || 2 ton anvil |+-------------+2 rows in set (0.00 sec)
mysql> select prod_name from products where prod_name regexp '[1-5] Ton';+--------------+| prod_name|+--------------+| .5 ton anvil || 1 ton anvil|| 2 ton anvil|+--------------+3 rows in set (0.02 sec)
mysql> select prod_name from products where prod_name regexp '[^1-3] Ton';+--------------+| prod_name|+--------------+| .5 ton anvil |+--------------+1 row in set (0.00 sec)
匹配特殊字符，必须用//为前导。
mysql> select prod_name from products where prod_name regexp '//.' ;+--------------+| prod_name|+--------------+| .5 ton anvil |+--------------+1 row in set (0.00 sec)
匹配字符类：
mysql> select prod_name from products where prod_name REGEXP '//([0-9] sticks?//)' order by prod_name;+----------------+| prod_name|+----------------+| TNT (1 stick)|| TNT (5 sticks) |+----------------+2 rows in set (0.05 sec)mysql> select prod_name from products where prod_name REGEXP '[[:digit:]]{4}' order by prod_name;+--------------+| prod_name|+--------------+| JetPack 1000 || JetPack 2000 |+--------------+2 rows in set (0.00 sec)定位符用法：
mysql> select prod_name -> from products -> where prod_name REGEXP '^[0-9//.]' -> order by prod_name;+--------------+| prod_name |+--------------+| .5 ton anvil || 1 ton anvil|| 2 ton anvil|+--------------+3 rows in set (0.00 sec)
