資料：http://blog.csdn.net/biandous/article/details/65630783
一、mapper接口中的方法解析
mapper接口中的函數(shù)及方法
方法功能說(shuō)明
int countByExample(UserExample example) thorws SQLException按條件計(jì)數(shù)
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(shù)據(jù)（返回值為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(dāng)數(shù)據(jù)表中的字段類(lèi)型有為二進(jìn)制的才會(huì)產(chǎn)生。
int updateByPrimaryKey(User record) thorws SQLException按主鍵更新
int updateByPrimaryKeySelective(User record) thorws SQLException按主鍵更新值不為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按條件更新值不為null的字段
mybatis的逆向工程中會(huì)生成實(shí)例及實(shí)例對(duì)應(yīng)的example，example用于添加條件，相當(dāng)where后面的部分?
xxxExample example = new xxxExample();?
Criteria criteria = new Example().createCriteria();
方法說(shuō)明
example.setOrderByClause(“字段名 ASC”);添加升序排列條件，DESC為降序
example.setDistinct(false)去除重復(fù)，boolean型，true為選擇不重復(fù)的記錄。
criteria.andXxxIsNull添加字段xxx為null的條件
criteria.andXxxIsNotNull添加字段xxx不為null的條件
criteria.andXxxEqualTo(value)添加xxx字段等于value條件
criteria.andXxxNotEqualTo(value)添加xxx字段不等于value條件
criteria.andXxxGreaterThan(value)添加xxx字段大于value條件
criteria.andXxxGreaterThanOrEqualTo(value)添加xxx字段大于等于value條件
criteria.andXxxLessThan(value)添加xxx字段小于value條件
criteria.andXxxLessThanOrEqualTo(value)添加xxx字段小于等于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字段值為value的模糊查詢條件
criteria.andXxxNotLike(“%”+value+”%”)添加xxx字段值不為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
criteria.andXxxNotBetween(value1,value2)添加xxx字段值不在value1和value2之間條件
1.查詢
① selectByPrimaryKey()
User user = XxxMapper.selectByPrimaryKey(100); //相當(dāng)于select*fromuserwhereid =100
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② selectByExample() 和 selectByExampleWithBLOGs()
UserExample example =newUserExample();Criteria criteria = example.createCriteria();criteria.andUsernameEqualTo("wyw");criteria.andUsernameIsNull();example.setOrderByClause("username asc,email desc");Listlist = XxxMapper.selectByExample(example);//相當(dāng)于：select* from user where username ='wyw'andusernameisnullorder by username asc,email desc
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注：在iBator逆向工程生成的文件XxxExample.java中包含一個(gè)static的內(nèi)部類(lèi)Criteria，Criteria中的方法是定義SQL 語(yǔ)句where后的查詢條件。
2.插入數(shù)據(jù)
①insert()
User user = new User();user.setId("dsfgsdfgdsfgds");user.setUsername("admin");user.setPassword("admin")user.setEmail("wyw@163.com");XxxMapper.insert(user);//相當(dāng)于：insertintouser(ID,username,password,email)values('dsfgsdfgdsfgds','admin','admin','wyw@126.com');
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3.更新數(shù)據(jù)
①u(mài)pdateByPrimaryKey()
User user =new User();user.setId("dsfgsdfgdsfgds");user.setUsername("wyw");user.setPassword("wyw");user.setEmail("wyw@163.com");XxxMapper.updateByPrimaryKey(user);//相當(dāng)于：update usersetusername='wyw', password='wyw', email='wyw@163.com'where id='dsfgsdfgdsfgds'
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②updateByPrimaryKeySelective()
User user = new User();user.setId("dsfgsdfgdsfgds");user.setPassword("wyw");XxxMapper.updateByPrimaryKey(user);//相當(dāng)于：updateusersetpassword='wyw'whereid='dsfgsdfgdsfgds'
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③ updateByExample() 和 updateByExampleSelective()
UserExample example = new UserExample();Criteria criteria = example.createCriteria();criteria.andUsernameEqualTo("admin");User user = new User();user.setPassword("wyw");XxxMapper.updateByPrimaryKeySelective(user,example);//相當(dāng)于：updateusersetpassword='wyw'whereusername='admin'
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updateByExample()更新所有的字段，包括字段為null的也更新，建議使用 updateByExampleSelective()更新想更新的字段
4.刪除數(shù)據(jù)
①deleteByPrimaryKey()
XxxMapper.deleteByPrimaryKey(1);? //相當(dāng)于：deletefromuserwhereid=1
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②deleteByExample()
UserExample example = new UserExample();Criteria criteria = example.createCriteria();criteria.andUsernameEqualTo("admin");XxxMapper.deleteByExample(example);//相當(dāng)于：deletefromuserwhereusername='admin'
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5.查詢數(shù)據(jù)數(shù)量
①countByExample()
UserExample example = new UserExample();Criteria criteria = example.createCriteria();criteria.andUsernameEqualTo("wyw");int count = XxxMapper.countByExample(example);//相當(dāng)于：selectcount(*)fromuserwhereusername='wyw'
