方法    功能说明

int countByExample(UserExample example) thorws SQLException    按条件计数

int deleteByPrimaryKey(Integer id) thorws SQLException    按主键删除

int deleteByExample(UserExample example) thorws SQLException    按条件查询

String/Integer insert(User record) thorws SQLException    插入数据（返回值为ID）

User selectByPrimaryKey(Integer id) thorws SQLException    按主键查询

ListselectByExample(UserExample example) thorws SQLException    按条件查询

ListselectByExampleWithBLOGs(UserExample example) thorws SQLException    按条件查询（包括BLOB字段）。只有当数据表中的字段类型有为二进制的才会产生。

int updateByPrimaryKey(User record) thorws SQLException    按主键更新

int updateByPrimaryKeySelective(User record) thorws SQLException    按主键更新值不为null的字段

int updateByExample(User record, UserExample example) thorws SQLException    按条件更新

int updateByExampleSelective(User record, UserExample example) thorws SQLException    按条件更新值不为null的字段

方法    说明

example.setOrderByClause(“字段名 ASC”);    添加升序排列条件，DESC为降序

example.setDistinct(false)    去除重复，boolean型，true为选择不重复的记录。

criteria.andXxxIsNull    添加字段xxx为null的条件

criteria.andXxxIsNotNull    添加字段xxx不为null的条件

criteria.andXxxEqualTo(value)    添加xxx字段等于value条件

criteria.andXxxNotEqualTo(value)    添加xxx字段不等于value条件

criteria.andXxxGreaterThan(value)    添加xxx字段大于value条件

criteria.andXxxGreaterThanOrEqualTo(value)    添加xxx字段大于等于value条件

criteria.andXxxLessThan(value)    添加xxx字段小于value条件

criteria.andXxxLessThanOrEqualTo(value)    添加xxx字段小于等于value条件

criteria.andXxxIn(List<？>)    添加xxx字段值在List<？>条件

criteria.andXxxNotIn(List<？>)    添加xxx字段值不在List<？>条件

criteria.andXxxLike(“%”+value+”%”)    添加xxx字段值为value的模糊查询条件

criteria.andXxxNotLike(“%”+value+”%”)    添加xxx字段值不为value的模糊查询条件

criteria.andXxxBetween(value1,value2)    添加xxx字段值在value1和value2之间条件

criteria.andXxxNotBetween(value1,value2)    添加xxx字段值不在value1和value2之间条件

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

UserExample example = 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

User user = new User();

user.setId("dsfgsdfgdsfgds");

user.setUsername("admin");

user.setPassword("admin")

user.setEmail("wyw@163.com");

XxxMapper.insert(user);

//相当于：insert into user(ID,username,password,email) values ('dsfgsdfgdsfgds','admin','admin','wyw@126.com');

User user =new User();

user.setId("dsfgsdfgdsfgds");

user.setUsername("wyw");

user.setPassword("wyw");

user.setEmail("wyw@163.com");

XxxMapper.updateByPrimaryKey(user);

//相当于：update user set username='wyw', password='wyw', email='wyw@163.com' where id='dsfgsdfgdsfgds'

User user = new User();

user.setId("dsfgsdfgdsfgds");

user.setPassword("wyw");

XxxMapper.updateByPrimaryKey(user);

//相当于：update user set password='wyw' where id='dsfgsdfgdsfgds'

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'

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

UserExample example = new UserExample();

Criteria criteria = example.createCriteria();

criteria.andUsernameEqualTo("admin");

XxxMapper.deleteByExample(example);

//相当于：delete from user where username='admin'

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'