The implementation method of PHP fuzzy query (recommended) _php instance

Mode query

1. SQL Match mode

2. Regular expression matching pattern (generally not recommended)

SQL match mode

1. Use SQL match mode, cannot use operator = or! =, instead of using the operator like or not like;

2. Using SQL matching mode, MySQL provides 2 wildcard characters.

% represents any number of any characters (including 0)

_ Represents any single character

3. Using SQL matching mode, if the matching format does not contain any of the above 2 wildcard characters, the query's effect equals = or! =

4. Use SQL match mode, match case case-insensitive

#查询用户名以某个字符开头的用户
#查询用户名以字符 ' l ' User: l%
SELECT * from user WHERE username like ' l% ';
#查询用户名以某个字符结尾的用户
#查询用户名以字符 ' e ' end User: e%
SELECT * from user WHERE username like ' e% ';
#查询用户名包含某个字符的用户
#查询用户名包含字符 ' o ':%o%
SELECT * from user WHERE username like '%o% ';
#查询包含三个字符的用户
SELECT * from user WHERE username like ' ___ ';
#查询用户名第二个字符为o的用户: _o%
SELECT * from user WHERE username like ' _o% ';

Regular expression matching pattern

wildcard character (regular expression)

. Match any single character

* Match 0 or more characters in front of it

x* means match any number of x characters

[..] Match any character in the brackets
[ABC] match character AB or C
[A-z] matches any letter
[0-9] matches any number
[0-9]* matches any number of any numbers
[a-z]* matches any number of letters

^ representation begins with a character or string

^a, beginning with the letter A

$ indicates ending with a character or string

s$ the end of the letter S

The operators used in a regular expression matching pattern are:

REGEXP or not REGEXP (rlike or not rlike)

Note: The regular expression matches the pattern, and its regular expression appears anywhere in the matching field.

Even if the pattern matches, it is not necessary to put a wildcard on both sides to make it match;

If only wildcard characters are used. To match, assuming N, then its matching pattern is expressed to be greater than or equal to N;

How do you understand the above remark?

So

... Match data greater than or equal to 3 characters
.... Match data greater than or equal to 4 characters
User with #查询用户名以字符 L: ^l;
#正则表达式写法

SELECT * FROM user WHERE username REGEXP ' ^l ';
#sql匹配模式写法:
SELECT * from user WHERE username like ' l% ';
#查询用户名正好是三个字符的用户: ^...$;
#sql匹配模式写法:
SELECT * from user WHERE username like ' ___ ';
#正则表达式写法
SELECT * from user WHERE username REGEXP ' ^...$ ';

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