Fun day three minutes MyBatis-Plus - 3. advanced query (a) (Conditions constructor)

Fun 3 minutes per day MyBatis-Plus - Configuration Environment

Fun day three minutes MyBatis-Plus - 2. General Queries

Fun 3 minutes MyBatis-Plus daily - 3. Advanced Search

Download: https: //github.com/Jackson0714/study-mybatis-plus.git

mybatis-plus search function is very powerful, the one we introduced the common queries mybatis-plus, which we introduced an advanced query features of mybatis-plus. Explained through several query requirements.

Prepare data

User Table structure is as follows:

id	name	age	email
1	Our	18	[email protected]
2	Jack	20	[email protected]
3	Tom	28	[email protected]
4	Sandy	21	[email protected]
5	Billie	24	[email protected]

 

 

First, the case summary (the first wave)

1.1 query name contains "Ja" and users younger than 30

Difficulty coefficient ★ ☆

1.2 query contains the name "a" and older than 15 and is equal to the age of 25 or less, and the email is not empty

Difficulty coefficient ★ ☆

1.3 at the beginning of the query the name "J" is equal to and greater than the age of 25, in descending order according to age, the same age, according to the ascending order id

Difficulty factor ★★★

Second, explain the case

1.1 query name contains "Ja" and users younger than 30

Difficulty coefficient ★ ☆

Visits like, lt usage

name LIKE '%Ja%' age < 30

1      / * 
2       * Description: Example 2.1 query name contains "Ja" and users younger than 30
 3       * Author: blog Garden - Wukong chat Architecture
 4       * Time: 2019-01-20
 5       * Github: HTTPS: // GitHub .com / Jackson0714 / Study-MyBatis-plus.git 
. 6       * blog Park: https://www.cnblogs.com/jackson0714 
. 7       * * / 
. 8      @Test
 . 9      public  void testSelectByQueryWrapper () {
 10          System.out.println (( "----- query contains the name" of Ja "and a user younger than 30 ------" ));
 . 11          QueryWrapper <the user> = queryWrapper new new QueryWrapper <> ();
 12 is         queryWrapper.like("name", "ja").lt("age", 30);
13         List<User> userList = userMapper.selectList(queryWrapper);
14         userList.forEach(System.out::println);
15     }

1.2 query contains the name "a" and older than 15 and is equal to the age of 25 or less, and the email is not empty

★ ☆ degree of difficulty of 
visits between usage

SQL语句：name LIKE '%a%' AND age BETWEEN 15 AND 25 AND email IS NOT NULL

1      / * 
2       * Description: Example 1.2 query contains the name "a" and older than 15 and is equal to the age of 35 or less, and the email is not empty
 3       * OF: blog Park - Monkey talk architecture
 4       * Time: 2019-01- 20
 5       * Github: https://github.com/Jackson0714/study-mybatis-plus.git 
6       * Park blog: https://www.cnblogs.com/jackson0714 
7       * * / 
8      @Test
 9      public  void testSelectByQueryWrapper2 ( ) {
 10          System.out.println (( "----- query contains the name" a "and older than 15 and is equal to the age of 25 or less, and the email is not empty ------" ));
 11          QueryWrapper <the User> = queryWrapper new new QueryWrapper <> ();
12         //queryWrapper.like("name", "a").ge("age", 15).le("age", 25).isNotNull("email");
13         queryWrapper.like("name", "a").between("age", 15,25).isNotNull("email");
14         List<User> userList = userMapper.selectList(queryWrapper);
15         userList.forEach(System.out::println);
16     }

 

 1.3 at the beginning of the query the name "J" is equal to and greater than the age of 25, in descending order according to age, the same age, according to the ascending order id

Difficulty factor  ★★★

Study likeRight, orderByDesc, orderByAsc usage

SQL语句：name LIKE 'J%' or age > 25 ORDER BY age desc, id ASC

1      / * 
2       * Description: Example 1.3 query the name "J" at the beginning and older than 26, in descending order according to age, the age of the same arranged in id ascending
 . 3       * the SQL statement: name LIKE 'J%' or age> 26 ORDER BY age desc, the above mentioned id ASC
 4       * author: blog garden - Wukong talk architecture
 5       * time: 2019-01-20
 6       * Github: https://github.com/Jackson0714/study-mybatis-plus.git 
7       * Park blog: HTTPS : //www.cnblogs.com/jackson0714 
. 8       * * / 
. 9      @Test
 10      public  void testSelectByQueryWrapper3 () {
 . 11          System.out.println (( "----- query contains the name" a "and older than 26, in descending order according to age, the same age, arranged in ascending order ------ id " ));
 12         QueryWrapper<User> queryWrapper = new QueryWrapper<>();
13         queryWrapper.likeRight("name","J").or().gt("age",26).orderByDesc("age")
14                 .orderByAsc("id");
15         List<User> userList = userMapper.selectList(queryWrapper);
16         userList.forEach(System.out::println);
17     }

 

 

 

Fun 3 minutes per day MyBatis-Plus - Configuration Environment

Fun day three minutes MyBatis-Plus - 2. General Queries

Fun 3 minutes MyBatis-Plus daily - 3. Advanced Search

 

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