mybatis中的mapper接口文件以及example类的实例函数以及详解

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##Example example = new ##Example();example.setOrderByClause("字段名 ASC"); //升序排列，desc为降序排列。example.setDistinct(false)//去除重复，boolean型，true为选择不重复的记录。Criteria criteria = new Example().createCriteria();is null;is not null;equal to(value);not equal to(value);GreaterThan(value);GreaterThanOrEqualTo(value);LessThan(value); LessThanOrEqualTo(value);in(item,item,item,...);not in(item,item,item,...);like("%"+value+"%");not like("%"+value+"%");Between(value1,value2);not between(value1,value2) mybatis中mapper的实例函数: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：按条件删除。String/Integer insert(User record) thorws SQLException：插入(返回值为id值)User selectByPrimaryKey(Integer id) thorws SQLException：按主键查询。List<?>selectByExample(UserExample example) thorws SQLException：按条件查询List<?>selectByExampleWithBLOGs(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mybatis中mapper的实例函数详解：① selectByPrimaryKey()User user = ##Mapper.selectByPrimaryKey(100); 相当于select * from user whereid = 100② selectByExample() 和 selectByExampleWithBLOGs()UserExample example = new UserExample();Criteria criteria = example.createCriteria();criteria.andUsernameEqualTo("joe");criteria.andUsernameIsNull();example.setOrderByClause("username asc,email desc");List<?>list = ##Mapper.selectByExample(example);相当于：select * from user where username = 'joe' and username is null orderby username asc,email desc注：在iBator 生成的文件UserExample.java中包含一个static 的内部类 Criteria ，在Criteria中有很多方法，主要是定义SQL 语句where后的查询条件。③ insert()User user = new User();user.setId(101);user.setUsername("test");user.setPassword("123")user.setEmail("joe@163.com");##Mapper.insert(user);相当于：insert into user(ID,username,password,email) values(101,'test','123','joe@163.com'); ④ updateByPrimaryKey() 和 updateByPrimaryKeySelective()User user =new User();user.setId(101);user.setUsername("joe");user.setPassword("joe");user.setEmail("joe@163.com");##Mapper.updateByPrimaryKey(user);相当于：update user set username='joe',password='joe',email='joe@163.com'where id=101User user = new User();user.setId(101);user.setPassword("joe");##Mapper.updateByPrimaryKeySelective(user);相当于：update user set password='joe' where id=101⑤ updateByExample() 和 updateByExampleSelective()UserExample example = new UserExample();Criteria criteria = example.createCriteria();criteria.andUsernameEqualTo("joe");User user = new User();user.setPassword("123");##Mapper.updateByPrimaryKeySelective(user,example);相当于：update user set password='123' where username='joe'⑥ deleteByPrimaryKey()##Mapper.deleteByPrimaryKey(101);  相当于：delete from user where id=101⑦ deleteByExample()UserExample example = new UserExample();Criteria criteria = example.createCriteria();criteria.andUsernameEqualTo("joe");##Mapper.deleteByExample(example);相当于：delete from user where username='joe'⑧ countByExample()UserExample example = new UserExample();Criteria criteria = example.createCriteria();criteria.andUsernameEqualTo("joe");int count = ##Mapper.countByExample(example);相当于：select count(*) from user where username='joe'
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