目錄
② selectByExample() 和 selectByExampleWithBLOGs()
② updateByPrimaryKeySelective()
③ updateByExample() 和 updateByExampleSelective()
mapper接口中的方法解析
mapper接口中的函數及方法
方法 |
功能說明 |
int countByExample(UserExample example) thorws SQLException |
按條件計數 |
int deleteByPrimaryKey(Integer id) thorws SQLException |
按主鍵刪除 |
int deleteByExample(UserExample example) thorws SQLException |
按條件查詢 |
String/Integer insert(User record) thorws SQLException |
插入數據(返回值爲ID) |
User selectByPrimaryKey(Integer id) thorws SQLException |
按主鍵查詢 |
ListselectByExample(UserExample example) thorws SQLException |
按條件查詢 |
ListselectByExampleWithBLOGs(UserExample example) thorws SQLException |
按條件查詢(包括BLOB字段)。只有當數據表中的字段類型有爲二進制的纔會產生。 |
int updateByPrimaryKey(User record) thorws SQLException |
按主鍵更新 |
int updateByPrimaryKeySelective(User record) thorws SQLException |
按主鍵更新值不爲null的字段 |
int updateByExample(User record, UserExample example) thorws SQLException |
按條件更新 |
int updateByExampleSelective(User record, UserExample example) thorws SQLException |
按條件更新值不爲null的字段 |
example實例解析
mybatis的逆向工程中會生成實例及實例對應的example,example用於添加條件,相當where後面的部分
xxxExample example = new xxxExample();
Criteria criteria = new Example().createCriteria();
方法 |
說明 |
example.setOrderByClause(“字段名 ASC”); |
添加升序排列條件,DESC爲降序 |
example.setDistinct(false) |
去除重複,boolean型,true爲選擇不重複的記錄。 |
criteria.andXxxIsNull |
添加字段xxx爲null的條件 |
criteria.andXxxIsNotNull |
添加字段xxx不爲null的條件 |
criteria.andXxxEqualTo(value) |
添加xxx字段等於value條件 |
criteria.andXxxNotEqualTo(value) |
添加xxx字段不等於value條件 |
criteria.andXxxGreaterThan(value) |
添加xxx字段大於value條件 |
criteria.andXxxGreaterThanOrEqualTo(value) |
添加xxx字段大於等於value條件 |
criteria.andXxxLessThan(value) |
添加xxx字段小於value條件 |
criteria.andXxxLessThanOrEqualTo(value) |
添加xxx字段小於等於value條件 |
criteria.andXxxIn(List<?>) |
添加xxx字段值在List<?>條件 |
criteria.andXxxNotIn(List<?>) |
添加xxx字段值不在List<?>條件 |
criteria.andXxxLike(“%”+value+”%”) |
添加xxx字段值爲value的模糊查詢條件 |
criteria.andXxxNotLike(“%”+value+”%”) |
添加xxx字段值不爲value的模糊查詢條件 |
criteria.andXxxBetween(value1,value2) |
添加xxx字段值在value1和value2之間條件 |
應用舉例
查詢
① selectByPrimaryKey()
相當於:
select * from user where id = 100
User user = XxxMapper.selectByPrimaryKey(100);
② selectByExample() 和 selectByExampleWithBLOGs()
相當於:
select * from user where username = 'wyw' and username is null order by username asc,email desc
Criteria criteria = example.createCriteria();
criteria.andUsernameEqualTo("wyw");
criteria.andUsernameIsNull();
example.setOrderByClause("username asc,email desc");
List<?>list = XxxMapper.selectByExample(example);
注:在iBator逆向工程生成的文件XxxExample.java中包含一個static的內部類Criteria,Criteria中的方法是定義SQL 語句where後的查詢條件。
插入數據
①insert()
相當於:
insert into user(ID,username,password,email) values ('dsfgsdfgdsfgds','admin','admin','[email protected]');
User user = new User();
user.setId("dsfgsdfgdsfgds");
user.setUsername("admin");
user.setPassword("admin")
user.setEmail("[email protected]");
XxxMapper.insert(user);
更新數據
① updateByPrimaryKey()
相當於:
update user set username='wyw', password='wyw', email='[email protected]' where id='dsfgsdfgdsfgds'
User user =new User();
user.setId("dsfgsdfgdsfgds");
user.setUsername("wyw");
user.setPassword("wyw");
user.setEmail("[email protected]");
XxxMapper.updateByPrimaryKey(user);
② updateByPrimaryKeySelective()
相當於:
update user set password='wyw' where id='dsfgsdfgdsfgds'
User user = new User();
user.setId("dsfgsdfgdsfgds");
user.setPassword("wyw");
XxxMapper.updateByPrimaryKey(user);
③ updateByExample() 和 updateByExampleSelective()
相當於:
update user set password='wyw' where username='admin'
UserExample example = new UserExample();
Criteria criteria = example.createCriteria();
criteria.andUsernameEqualTo("admin");
User user = new User();
user.setPassword("wyw");
XxxMapper.updateByPrimaryKeySelective(user,example);
updateByExample()更新所有的字段,包括字段爲null的也更新,建議使用 updateByExampleSelective()更新想更新的字段
刪除數據
① deleteByPrimaryKey()
相當於:
delete from user where id=1
XxxMapper.deleteByPrimaryKey(1);
② deleteByExample()
相當於:
delete from user where username='admin'
UserExample example = new UserExample();
Criteria criteria = example.createCriteria();
criteria.andUsernameEqualTo("admin");
XxxMapper.deleteByExample(example);
查詢數據數量
① countByExample()
相當於:
select count(*) from user where username='wyw'
UserExample example = new UserExample();
Criteria criteria = example.createCriteria();
criteria.andUsernameEqualTo("wyw");
int count = XxxMapper.countByExample(example);