Related knowledge about Php+mysql fuzzy query function

Php+mysql Fuzzy query function is very important for PHP operation database, this article will explain its related knowledge in detail.

General Fuzzy query statements are as follows:

SELECT field from table WHERE a field like condition

With regard to the conditions, SQL provides four matching modes:

1,%: Represents any of 0 or more characters. Can match any type and length of the character, in some cases, if Chinese, please use two percent sign (%).
For example SELECT * from [user] WHERE u_name like '% three '
will be u_name for "Zhang San", "Zhang Cat Three", "three-legged Cat", "Tang Sanzang" and so on Have "three" records all find out.
Also, if you need to find a record of "three" and "cat" in U_name, use the and condition
SELECT * FROM [user] WHERE u_name like '% three ' and u_name like '% cat% '
If using SELECT * from [user] WHERE u_name like '% cat% '
Although can search out "three feet cat", but can not search out the eligible "Zhang Cat three".

2,_: Represents any single character. Matches a single arbitrary character, which is commonly used to restrict the expression's character-length statement:

For example SELECT * from [user] WHERE u_name like ' _ Three _ '
Only find "Tang Sanzang" so u_name for three words and the middle of a word is "three";

Another example is SELECT * from [user] WHERE u_name like ' three ';
Just find out "three-legged cat" this name is three words and the first word is "three";

3,[]: Represents one of the characters listed in parentheses (similar to a regular expression). Specifies a character, string, or range that requires matching objects to be any of them.

such as SELECT * from [user] WHERE u_name like ' [Zhang Li Wang] three '
Will find "Zhang San", "Lie Triple", "Wang San" (not "Zhangli Kang");

such as [] a series of characters (01234, ABCDE, etc.) can be slightly written as "0-4", "A-E"
SELECT * FROM [user] WHERE u_name like ' old [1-9] '
Will find "Old 1", "Old 2" 、......、 "Old 9";

4,[^]: Represents a single character that is not listed in parentheses. The value is the same as [], but it requires that the matched object be any character other than the specified character.

such as SELECT * from [user] WHERE u_name like ' [^ Zhang Li Wang] three '
Will find the surname "Zhang", "Li", "Wang" "Zhao Three", "Magozo" and so on;

SELECT * FROM [user] WHERE u_name like ' old [^1-4] ';
Will exclude "old 1" to "Old 4", Looking for "old 5", "Old 6" 、......

5, query content contains wildcard characters

Because of the wildcard character, which causes us to query the special characters "%", "_", "[" the statement can not be implemented normally, and the special characters with "[]" in the normal query. Thus we write the following function:

function Sqlencode (str) str=replace (str, "[", "[[]") ' This sentence must be in the first str=replace (str, "_", "[_]") Str=replace (str, "%", "[%]") Sqlencode=strend function

This article for the Php+mysql Fuzzy query function of the relevant explanation, more learning materials clear focus on the PHP Chinese network can be viewed.