A detailed explanation of SQL Fuzzy query statement

To implement a fuzzy query in SQL We just need to use like to be able to achieve, with some of the middle of the parameters such as%? And so on, let's look at an example.
Like operator
The LIKE operator is used to search for a specified pattern in a column in a WHERE clause.

SQL Like operator syntax

SELECT column_name (s) from Table_namewhere column_name like

1> CREATE TABLE Employee (emp_no INTEGER not NULL,
2> emp_fname CHAR (not NULL),
3> emp_lname CHAR (not NULL),
4> dept_no CHAR (4) NULL)
5> Go
1> INSERT into employee values (1, ' Matthew ', ' Smith ', ' D3 ')
2> INSERT into employee values (2, ' Ann ', ' Jones ', ' D3 ')
3> INSERT into employee values (3, ' John ', ' barrimore ', ' D1 ')
4> INSERT into employee values (4, ' James ', ' James ', ' D2 ')
5> INSERT into employee values (5, ' Elsa ', ' Bertoni ', ' D2 ')
6> INSERT into employee values (6, ' Elke ', ' Hansel ', ' D2 ')
7> INSERT into employee values (7, ' Sybill ', ' Moser ', ' D1 ')
8> Go

> SELECT * FROM Employee WHERE emp_fname isn't like '%n '
4> Go
Emp_no emp_fname Emp_lname Dept_no
----------- -------------------- -------------------- -------
1 Matthew Smith D3
4 James James D2
5 Elsa Bertoni D2
6 Elke Hansel D2
7 Sybill Moser D1

Example Two

2> SELECT *
3> from Employee
4> WHERE Name like "%[k-l]%"
5> Go
ID Name Salary start_date City Region
----------- ---------- ----------- ----------------------- ---------- ------
3 Celia 24020 1996-12-03 00:00:00.000 Toronto W
4 Linda 40620 1997-11-04 00:00:00.000 New York N
7 Alison 90620 2000-08-07 00:00:00.000 New York W

About like%

#% represents any number of characters

SELECT * from user where username like '%huxiao ';

SELECT * from user where username like ' huxiao% ';

SELECT * from user where username like '%huxiao% ';

#% represents a character

SELECT * from user where username like ' _ ';

SELECT * from user where username like ' ___ ';

SELECT * from user where username like ' Huxia_ ';

SELECT * from user where username like ' H_xiao ';

If I really want to check% or _, how to do? Using escape, the% or _ after the escape character is not used as a wildcard, noting that the% and _ of the previous escape characters are still in the wildcard role

Select username from Gg_user where username like '%xiao/_% ' escape '/';
Select username from Gg_user where username like '%xiao/%% ' escape '/';

About wildcard characters

' A_z ': All characters that start with ' A ', another word of any value, and a string ending with ' Z '. Both ' Abz ' and ' a2z ' conform to this pattern, and ' akkz ' does not conform (because there are two characters between A and Z, not a single word).
' abc% ': all the strings starting with ' ABC '. For example, ' ABCD ' and ' abcabc ' all fit this set.
'%XYZ ': all strings ending with ' XYZ '. For example, ' wxyz ' and ' zzxyz ' are consistent with this set.
'%an% ': All containing ' an ' this set of strings. For example, both ' LOS ANGELES ' and ' SAN FRANCISCO ' fit this set.

In SQL, you can use the following wildcard characters:

wildcard characters	Description
%	Replace one or more characters
_	Replace only one character
[Charlist]	Word columns any single character
[^charlist] Or [!charlist]	Not a word columns any single