SQL_STUDY: 5.LIKE and wildcards

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Summary:

1. like 加 ‘%ss%’
2. not like
3. mybatis uses concat
4. Tsuhaifu

SQL LIKE operator

LIKE operator is used in the WHERE clause specifies the column search pattern.

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LIKE operator

LIKE operator is used in the WHERE clause specifies the column search pattern.

SQL LIKE operator syntax

SELECT column_name(s)
FROM table_name
WHERE column_name LIKE pattern

Now we want to choose people living in cities beginning with "N" in from the top of the "Persons" table:

We can use the following SELECT statement:

SELECT * FROM Persons
WHERE City LIKE 'N%'

Next, we want to choose people live in cities with "g" in the end from the "Persons" table:

We can use the following SELECT statement:

SELECT * FROM Persons
WHERE City LIKE '%g'

SELECT * FROM Persons
WHERE City LIKE '%lon%'

The use mybatis

concat splicing

concat(concat (’%’,#{foldername}),’%’)

foldername like concat(concat ('%',#{foldername}),'%')

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SQL wildcard

SQL wildcard

When data in the search database, SQL wildcards can substitute one or more characters.

It must be used with SQL wildcard LIKE operator.

In SQL, you can use the following wildcards:

Tsuhaifu	description
%	Replace one or more characters
_	Replace only one character
[charlist]	Character any single character column
[^ Charlist] or [! Charlist]	Not in the character of any single character column

The original table (used in the example):

Persons 表:
Id LastName FirstName Address City
1 Adams John Oxford Street London
2 Bush George Fifth Avenue New York
3 Carter Thomas Changan Street Beijing

Use% wildcard

Now we want to choose people living in cities beginning with "Ne" in from the top of the "Persons" table:

We can use the following SELECT statement:

SELECT * FROM Persons
WHERE City LIKE 'Ne%'

The results set:
Id LastName FirstName Address City
2 George Bush Fifth Avenue New York
Example 2

Next, we want to choose people live in the city include "lond" from the inside "Persons" table:

We can use the following SELECT statement:

SELECT * FROM Persons
WHERE City LIKE '%lond%'

结果集：
Id LastName FirstName Address City
1 Adams John Oxford Street London

_ Use Wildcards

Example 1
Now we want to select the name after the first character from above "Persons" table is "eorge" people:

We can use the following SELECT statement:

SELECT * FROM Persons
WHERE FirstName LIKE '_eorge'

The results set:
Id LastName FirstName Address City
2 George Bush Fifth Avenue New York
Example 2
Next, we want to choose from the "Persons" table in this record last name begins with "C", then any character, then " r ", then any character, then" er ":

We can use the following SELECT statement:

SELECT * FROM Persons
WHERE LastName LIKE 'C_r_er'

结果集：
Id LastName FirstName Address City
3 Carter Thomas Changan Street Beijing

Using [the charlist] wildcard

Example 1
Now we want to choose the city to live with "A" or "L" or "N" from the beginning of man above "Persons" table:

We can use the following SELECT statement:

SELECT * FROM Persons
WHERE City LIKE '[ALN]%'

The results set:
Id LastName FirstName Address City
1 Adams John Oxford Street London
2 Bush George Fifth Avenue New York
Example 2
Now we want the city from above "Persons" table, choose to live not to "A" or "L" or " N "at the beginning of people:

We can use the following SELECT statement:

SELECT * FROM Persons
WHERE City LIKE '[!ALN]%'

结果集：
Id LastName FirstName Address City
3 Carter Thomas Changan Street Beijing