MyBatis Mapper Interface and example instance functions and explanations

Method parsing in Mapper interface

Functions and methods in the Mapper interface

Method	function Description
int Countbyexample (userexample example) Thorws SQLException	Count by criteria
int Deletebyprimarykey (Integer id) thorws SQLException	Delete by primary key
int Deletebyexample (userexample example) Thorws SQLException	Query by criteria
String/integer Insert (User record) Thorws SQLException	Insert data (return value is ID)
User Selectbyprimarykey (Integer ID) thorws SQLException	Query by PRIMARY key
Listselectbyexample (userexample example) Thorws SQLException	Query by criteria
Listselectbyexamplewithblogs (userexample example) Thorws SQLException	Query by criteria (including BLOB fields). Only if the field type in the data table is binary is it generated.
int Updatebyprimarykey (User record) Thorws SQLException	Press the primary key to update
int updatebyprimarykeyselective (User record) Thorws SQLException	Update a field with a value that is not NULL by the primary key
int Updatebyexample (User record, userexample example) Thorws SQLException	Update by condition
int updatebyexampleselective (User record, userexample example) Thorws SQLException	Update a field with a value that is not NULL by condition

Second, example case analysis

MyBatis in reverse engineering will generate instances and instances corresponding to the example,example used to add conditions, quite where the later part
xxxexample example = new Xxxexample ();
criteria = new Example (). Createcriteria ();

Method	Description
Example.setorderbyclause ("Field name ASC");	Add ascending sort condition, desc is descending
Example.setdistinct (False)	Remove Duplicates, Boolean, True to select records that are not duplicates.
Criteria.andxxxisnull	Add a field XXX null condition
Criteria.andxxxisnotnull	Add field XXX non-null condition
Criteria.andxxxequalto (value)	Add xxx field equals value condition
Criteria.andxxxnotequalto (value)	Adding the XXX field is not equal to the value condition
Criteria.andxxxgreaterthan (value)	Add the XXX field is greater than the value condition
Criteria.andxxxgreaterthanorequalto (value)	Add the XXX field is greater than or equal to the value condition
Criteria.andxxxlessthan (value)	Adding the xxx field is less than the value condition
Criteria.andxxxlessthanorequalto (value)	Add the xxx field is less than or equal to the value condition
Criteria.andxxxin (list<? >)	Add xxx field value in List<? > Conditions
Criteria.andxxxnotin (list<? >)	Add XXX field value not list<? > Conditions
Criteria.andxxxlike ("%" +value+ "%")	Add a fuzzy query condition with a value of XXX field
Criteria.andxxxnotlike ("%" +value+ "%")	Add a fuzzy query condition with the XXX field value not being value
Criteria.andxxxbetween (value1,value2)	Add the XXX field values between value1 and value2 conditions
Criteria.andxxxnotbetween (value1,value2)	Adding the XXX field value is not a condition between value1 and value2

Iii. examples of application 1. Enquiry

①selectbyprimarykey ()

User user = XxxMapper.selectByPrimaryKey(100); //相当于select * from user where id = 100

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②selectbyexample () and Selectbyexamplewithblogs ()

new UserExample();Criteria criteria = example.createCriteria();criteria.andUsernameEqualTo("wyw");criteria.andUsernameIsNull();example.setOrderByClause("username asc,email desc");List<?>list = XxxMapper.selectByExample(example);//相当于：select * from user where username = ‘wyw‘ and username is null order by username asc,email desc

Note: The Ibator reverse engineering generated file Xxxexample.java contains a static inner class Criteria,criteria method that defines the query condition after the SQL statement where.

2. Inserting data

①insert ()

User user = new User();user.setId("dsfgsdfgdsfgds");user.setUsername("admin");user.setPassword("admin")user.setEmail("[email protected]");XxxMapper.insert(user);//相当于：insert into user(ID,username,password,email) values (‘dsfgsdfgdsfgds‘,‘admin‘,‘admin‘,‘[email protected]‘);

3. Updating data

①updatebyprimarykey ()

User user =new User();user.setId("dsfgsdfgdsfgds");user.setUsername("wyw");user.setPassword("wyw");user.setEmail("[email protected]");XxxMapper.updateByPrimaryKey(user);//相当于：update user set username=‘wyw‘, password=‘wyw‘, email=‘[email protected]‘ where id=‘dsfgsdfgdsfgds‘

②updatebyprimarykeyselective ()

User user = new User();user.setId("dsfgsdfgdsfgds");user.setPassword("wyw");XxxMapper.updateByPrimaryKey(user);//相当于：update user set password=‘wyw‘ where id=‘dsfgsdfgdsfgds‘

③updatebyexample () and updatebyexampleselective ()

UserExample example = new UserExample();Criteria criteria = example.createCriteria();criteria.andUsernameEqualTo("admin");User user = new User();user.setPassword("wyw");XxxMapper.updateByPrimaryKeySelective(user,example);//相当于：update user set password=‘wyw‘ where username=‘admin‘

Updatebyexample () Update all fields, including NULL, are also updated, we recommend using Updatebyexampleselective () to update the fields you want to update

4. Delete data

①deletebyprimarykey ()

XxxMapper.deleteByPrimaryKey(1);  //相当于：delete from user where id=1

②deletebyexample ()

UserExample example = new UserExample();Criteria criteria = example.createCriteria();criteria.andUsernameEqualTo("admin");XxxMapper.deleteByExample(example);//相当于：delete from user where username=‘admin‘

5. Query the number of data

①countbyexample ()

UserExample example = new UserExample();Criteria criteria = example.createCriteria();criteria.andUsernameEqualTo("wyw");int count = XxxMapper.countByExample(example);//相当于：select count(*) from user where username=‘wyw‘

MyBatis Mapper Interface and example instance functions and explanations