Select field from table where a field like Condition

Select field from table where a field like Condition
SQL provides four matching modes for conditions:

1, %: represents any 0 or multiple characters. It can match any type and length of characters. In some cases, if it is Chinese, use two percent signs (%. For example, if select * from [user] Where u_name like '% 3%', u_name is set to "Zhang San", "Zhang Mao San", and "three-legged cats ", "Tang sanzang" and so on have all records of "3. In addition, if you need to find records with "three" and "cat" in u_name, use the and condition, select * from [user] Where u_name like '% 3%' and u_name like '% cat % ', if you use select * from [user] Where u_name like '% 3% cat %', although you can search for three-legged cats, you cannot find the three-legged cats that meet the search criteria ".

2, _: represents any single character. Matches any character. It is often used to limit the character length of an expression: for example, select * from [user] Where u_name like '_ 3 _' only finds "Tang sanzang". In this way, u_name is three characters and the middle word is "three; for example, select * from [user] Where u_name like 'three _ '; only the three-legged cat is found. The name is three characters and the first word is "three.

3, []: represents one of the characters listed in brackets (similar to a regular expression ). Specifies a character, string, or range. The matching object must be one of them. For example, select * from [user] Where u_name like '[Zhang Li Wang] san' will find "Zhang San", "Li San", and "Wang San" (rather than "Zhang Li Wang San "); for example, [] contains a series of characters (01234, ABCDE, and so on) it can be written as "0-4", "a-e" select * from [user] Where u_name like 'Old [1-9] ', will find "Old 1", "old 2 ",...... And "old 9 ".

4, [^]: represents a single character 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. For example, select * from [user] Where u_name like '[^ Zhang Li Wang] san' will find "Zhao San" without the surname "Zhang", "Li", and "Wang ", sun San and others; select * from [user] Where u_name like 'Old [^ 1-4] '; will exclude "Old 1" to "old 4 ", search for "old 5", "old 6 ",......

5. When the query content contains wildcards, the special characters "%", "_", and "[" cannot be properly queried due to the wildcard, when special characters are included in "[]", they can be queried normally. Based on this, we write the following function: function sqlencode (STR) STR = Replace (STR, "[", "[]") ', which must be at the beginning of STR = Replace (STR, "_", "[_]") STR = Replace (STR, "%", "[%]") sqlencode = STR end function process the string to be queried before query.

This article is from "playing Linux... O & M... Cluster blog, be sure to keep this source http://scottlinn.blog.51cto.com/829656/1567797

Select field from table where a field like Condition