int countByExample(BUserExample example); //根据条件查询数量
/**
* 示例
* public int countByExample() {
* BUserExample userExample = new BUserExample();
* BUserExample.Criteria criteria = userExample.createCriteria();
* criteria.andUsernameEqualTo("fan");
* int count = userMapper.countByExample(userExample);
* return count;
* }
* 相当于：select count(*) from user where username = 'fan'
*/
int deleteByExample(BUserExample example); //根据条件删除数据(一条或多条)
/**
* 示例
* public int deleteByExample() {
* BUserExample userExample = new BUserExample();
* BUserExample.Criteria criteria = userExample.createCriteria();
* criteria.andUsernameEqualTo("fan");
* int count = userMapper.deleteByExample(userExample);
* return count;
* }
* 相当于：delete from user where username = 'fan'
*/
int deleteByPrimaryKey(Integer id); //根据主键删除数据
int insert(BUser record); //插入数据(插入一条数据)
int insertSelective(BUser record); //插入数据(插入一条数据,只插入不为null的字段,不会影响有默认值的字段)
List<BUser> selectByExample(BUserExample example); //根据条件查询数据
/**
* 示例：
* public List<BUser> getList() {
* BUserExample userExample = new BUserExample();
* BUserExample.Criteria criteria = userExample.createCriteria();
* criteria.andUsernameEqualTo("fan");
* userExample.setOrderByClause("username desc");
* List<BUser> users = userMapper.selectByExample(userExample);
* return users;
* }
* 相当于：select * from user where username = 'fan' order by username desc
*/
BUser selectByPrimaryKey(Integer id); //根据主键查询
int updateByExampleSelective(@Param("record") BUser record, @Param("example") BUserExample example); //按条件更新值不为null的字段
/**
* 示例：
* public int updateByParam(String username) {
* BUserExample userExample = new BUserExample();
* BUserExample.Criteria criteria = userExample.createCriteria();
* criteria.andUsernameEqualTo(username);
* BUser user = new BUser();
* user.setNickname("jdk");
* int update = userMapper.updateByExampleSelective(user, userExample);
* return update;
* }
* 相当于：update user set nickname = 'jdk' where username = #{username}
*/
int updateByExample(@Param("record") BUser record, @Param("example") BUserExample example); //按条件更新
int updateByPrimaryKeySelective(BUser record); //根据主键与条件更新
/**
* 示例：
* public int updateByIdAndParam(String username) {
* BUser user = new BUser();
* user.setId(101);
* user.setUsername(username);
* int update = userMapper.updateByPrimaryKeySelective(user);
* return update;
* }
* 相当于：update user set username = #{username} where id = 101
*/
int updateByPrimaryKey(BUser record); //根据主键更新
原文链接：https://blog.csdn.net/feidao0/article/details/80731824
