MySQL正则表达式简介
备注:测试数据库版本为MySQL 8.0
这个blog我们来聊聊MySQL的正则表达式
| 函数名 | 函数用途 |
|---|---|
| REGEXP_INSTR() | 指定位置开始是否符合正则表达式 |
| REGEXP_LIKE() | 判断字符串是否符合正则表达式，同义词RLIKE REGEXP |
| REGEXP_REPLACE() | 替换满足正则表达式的字符 |
| REGEXP_SUBSTR() | 返回符合正则的字符串 |
文章目录
- 一.REGEXP_INSTR()
- 二.REGEXP_LIKE()
- 三.regexp_replace()
- 四.regexp_substr
一.REGEXP_INSTR()
语法:
REGEXP_INSTR(expr, pat[, pos[, occurrence[, return_option[, match_type]]]])
-- 从第1个字符串开始查找，匹配字符','第1次出现的位置
select regexp_instr('abc,ABC,AAA,aaa',',',1,1);
-- 从第1个字符串开始查找，匹配字符','第2次出现的位置
select regexp_instr('abc,ABC,AAA,aaa',',',1,2);
-- 从第5个字符串开始查找，匹配字符','第2次出现的位置
select regexp_instr('abc,ABC,AAA,aaa',',',5,2);
-- 从第1个字符串开始查找，匹配字符','第2次出现的当前位置
select regexp_instr('abc,ABC,AAA,aaa',',',1,2,0);
-- 从第1个字符串开始查找，匹配字符','第2次出现的位置之后
select regexp_instr('abc,ABC,AAA,aaa',',',1,2,1);
mysql> -- 从第1个字符串开始查找，匹配字符','第1次出现的位置
mysql> select regexp_instr('abc,ABC,AAA,aaa',',',1,1);
+-----------------------------------------+
| regexp_instr('abc,ABC,AAA,aaa',',',1,1) |
+-----------------------------------------+
| 4 |
+-----------------------------------------+
1 row in set (0.00 sec)
mysql>
mysql> -- 从第1个字符串开始查找，匹配字符','第2次出现的位置
mysql> select regexp_instr('abc,ABC,AAA,aaa',',',1,2);
+-----------------------------------------+
| regexp_instr('abc,ABC,AAA,aaa',',',1,2) |
+-----------------------------------------+
| 8 |
+-----------------------------------------+
1 row in set (0.00 sec)
mysql>
mysql> -- 从第5个字符串开始查找，匹配字符','第2次出现的位置
mysql> select regexp_instr('abc,ABC,AAA,aaa',',',5,2);
+-----------------------------------------+
| regexp_instr('abc,ABC,AAA,aaa',',',5,2) |
+-----------------------------------------+
| 12 |
+-----------------------------------------+
1 row in set (0.00 sec)
mysql>
mysql> -- 从第1个字符串开始查找，匹配字符','第2次出现的当前位置
mysql> select regexp_instr('abc,ABC,AAA,aaa',',',1,2,0);
+-------------------------------------------+
| regexp_instr('abc,ABC,AAA,aaa',',',1,2,0) |
+-------------------------------------------+
| 8 |
+-------------------------------------------+
1 row in set (0.00 sec)
mysql>
mysql> -- 从第1个字符串开始查找，匹配字符','第2次出现的位置之后
mysql> select regexp_instr('abc,ABC,AAA,aaa',',',1,2,1);
+-------------------------------------------+
| regexp_instr('abc,ABC,AAA,aaa',',',1,2,1) |
+-------------------------------------------+
| 9 |
+-------------------------------------------+
1 row in set (0.00 sec)
mysql>
二.REGEXP_LIKE()
regexp_like语法:
regexp_like(src, pattern[, match])
regexp_like是like的加强版，使用频率非常高
-- regexp_like(src,'^A') 相当于:like 'A%'
SELECT str from (
select 'A' str union all select 'AB' str union all select 'BA' str union all select 'BACD' str
) tmp
where regexp_like(str,'^A');
-- regexp_like(src,'A$') 相当于:like '%A'
SELECT str from (
select 'A' str union all select 'AB' str union all select 'BA' str union all
select 'BACD' str
) tmp
where regexp_like(str,'A$');
-- regexp_like(src,'^A$')相当于:like 'A'
SELECT str from (
select 'A' str union all select 'AB' str union all select 'BA' str union all
select 'BACD' str
) tmp
where regexp_like(str,'^A$');
-- regexp_like(str,'^[ABC]')相当于： like '%A%' or like'%B%' or like'%C%'
SELECT str
FROM (select 'A' str union all select 'AB' str union all select 'BA' str union all
select 'BACD' str) tmp
WHERE regexp_like(str,'^[ABC]');
-- regexp_like(src,'[0-9a-zA-Z]+') 相当于：like '%数字%' or like '%小写字母%' or like '%大写字母%'
SELECT str
FROM (SELECT '12345' str
UNION ALL
SELECT 'abcde' str
UNION ALL
SELECT '12cde' str
UNION ALL
SELECT 'abc12' str
UNION ALL
SELECT 'a1b2cde' str
UNION ALL
SELECT '12345#' str
UNION ALL
SELECT 'abcde#' str
) tmp
WHERE regexp_like(str, '^[0-9a-zA-Z]+$');
-- "+"表示匹配前面的子表达式一次或多次
SELECT str from (
select '167' str union all select '1234567' str union all select '12666' str union all select '16666' str
) tmp
where regexp_like(str,'16+');
-- "*"表示匹配前面的子表达式零次或多次
SELECT str from (
select '167' str union all select '1234567' str union all select '12666' str union all select '16666' str
) tmp
where regexp_like(str,'16*');
mysql> -- regexp_like(src,'^A') 相当于:like 'A%'
mysql> SELECT str from (
-> select 'A' str union all select 'AB' str union all select 'BA' str union all select 'BACD' str
-> ) tmp
-> where regexp_like(str,'^A');
+-----+
| str |
+-----+
| A |
| AB |
+-----+
2 rows in set (0.00 sec)
mysql>
mysql> -- regexp_like(src,'A$') 相当于:like '%A'
mysql> SELECT str from (
-> select 'A' str union all select 'AB' str union all select 'BA' str union all
-> select 'BACD' str
-> ) tmp
-> where regexp_like(str,'A$');
+-----+
| str |
+-----+
| A |
| BA |
+-----+
2 rows in set (0.00 sec)
mysql>
mysql> -- regexp_like(src,'^A$')相当于:like 'A'
mysql> SELECT str from (
-> select 'A' str union all select 'AB' str union all select 'BA' str union all
-> select 'BACD' str
-> ) tmp
-> where regexp_like(str,'^A$');
+-----+
| str |
+-----+
| A |
+-----+
1 row in set (0.00 sec)
mysql>
mysql>
mysql> -- regexp_like(str,'^[ABC]')相当于： like '%A%' or like'%B%' or like'%C%'
mysql> SELECT str
-> FROM (select 'A' str union all select 'AB' str union all select 'BA' str union all
-> select 'BACD' str) tmp
-> WHERE regexp_like(str,'^[ABC]');
+------+
| str |
+------+
| A |
| AB |
| BA |
| BACD |
+------+
4 rows in set (0.00 sec)
mysql>
mysql>
mysql> -- regexp_like(src,'[0-9a-zA-Z]+') 相当于：like '%数字%' or like '%小写字母%' or like '%大写字母%'
mysql> SELECT str
-> FROM (SELECT '12345' str
->
-> UNION ALL
-> SELECT 'abcde' str
->
-> UNION ALL
-> SELECT '12cde' str
->
-> UNION ALL
-> SELECT 'abc12' str
->
-> UNION ALL
-> SELECT 'a1b2cde' str
->
-> UNION ALL
-> SELECT '12345#' str
->
-> UNION ALL
-> SELECT 'abcde#' str
-> ) tmp
-> WHERE regexp_like(str, '^[0-9a-zA-Z]+$');
+---------+
| str |
+---------+
| 12345 |
| abcde |
| 12cde |
| abc12 |
| a1b2cde |
+---------+
5 rows in set (0.00 sec)
mysql>
mysql>
mysql> -- "+"表示匹配前面的子表达式一次或多次
mysql> SELECT str from (
-> select '167' str union all select '1234567' str union all select '12666' str union all select '16666' str
-> ) tmp
-> where regexp_like(str,'16+');
+-------+
| str |
+-------+
| 167 |
| 16666 |
+-------+
2 rows in set (0.00 sec)
mysql>
mysql> -- "*"表示匹配前面的子表达式零次或多次
mysql> SELECT str from (
-> select '167' str union all select '1234567' str union all select '12666' str union all select '16666' str
-> ) tmp
-> where regexp_like(str,'16*');
+---------+
| str |
+---------+
| 167 |
| 1234567 |
| 12666 |
| 16666 |
+---------+
4 rows in set (0.00 sec)
mysql>
mysql>
三.regexp_replace()
regexp_replace语法:
regexp_replace(src, pattern[, replace_str[, pos[, occur[, match]]]])
regexp_replace是replace的加强版，使用频率非常高
-- 去掉字符串中的AEIOU字符
select regexp_replace('ABCDEFGHI','[AEIOU]');
-- 去掉字符串中的非AEIOU字符
select regexp_replace('ABCDEFGHI','[^AEIOU]');
-- 从第5个字符开始去掉字符串中的AEIOU字符
select regexp_replace('ABCDEFGHI','[AEIOU]','',5);
-- 从第5个字符开始去掉第二次出现字符串中的AEIOU字符
select regexp_replace('ABCDEFGHI','[AEIOU]','',5,2);
mysql> -- 去掉字符串中的AEIOU字符
mysql> select regexp_replace('ABCDEFGHI','[AEIOU]');
ERROR 1582 (42000): Incorrect parameter count in the call to native function 'regexp_replace'
mysql>
mysql> -- 去掉字符串中的非AEIOU字符
mysql> select regexp_replace('ABCDEFGHI','[^AEIOU]');
ERROR 1582 (42000): Incorrect parameter count in the call to native function 'regexp_replace'
mysql>
mysql> -- 从第5个字符开始去掉字符串中的AEIOU字符
mysql> select regexp_replace('ABCDEFGHI','[AEIOU]','',5);
+--------------------------------------------+
| regexp_replace('ABCDEFGHI','[AEIOU]','',5) |
+--------------------------------------------+
| ABCDFGH |
+--------------------------------------------+
1 row in set (0.00 sec)
mysql>
mysql> -- 从第5个字符开始去掉第二次出现字符串中的AEIOU字符
mysql> select regexp_replace('ABCDEFGHI','[AEIOU]','',5,2);
+----------------------------------------------+
| regexp_replace('ABCDEFGHI','[AEIOU]','',5,2) |
+----------------------------------------------+
| ABCDEFGH |
+----------------------------------------------+
1 row in set (0.00 sec)
四.regexp_substr
regexp_substr语法:
regexp_substr(src, pattern[, pos[, occur[, match[, subexpr]]]])
regexp_substr就是substr的加强版
-- 用正则分隔的第一个值是192
SELECT REGEXP_SUBSTR('192.168.16.18','[^.]+',1,1,'i') AS STR;
-- 拆分IP
SELECT regexp_substr(ip, '[^.]+', 1, 1) a,
regexp_substr(ip, '[^.]+', 1, 2) b,
regexp_substr(ip, '[^.]+', 1, 3) c,
regexp_substr(ip, '[^.]+', 1, 4) d
FROM (SELECT '192.168.16.18' AS ip FROM dual) tmp;
mysql> SELECT REGEXP_SUBSTR('192.168.16.18','[^.]+',1,1,'i') AS STR;
+-----+
| STR |
+-----+
| 192 |
+-----+
1 row in set (0.00 sec)
mysql>
mysql> SELECT regexp_substr(ip, '[^.]+', 1, 1) a,
-> regexp_substr(ip, '[^.]+', 1, 2) b,
-> regexp_substr(ip, '[^.]+', 1, 3) c,
-> regexp_substr(ip, '[^.]+', 1, 4) d
-> FROM (SELECT '192.168.16.18' AS ip FROM dual) tmp;
+-----+-----+----+----+
| a | b | c | d |
+-----+-----+----+----+
| 192 | 168 | 16 | 18 |
+-----+-----+----+----+
1 row in set (0.00 sec)