mybatis注解开发

主要是下面4个注解
@Select @Insert @Update @Delete

001-@Select

1 2	`@Select("select * from user")` `List<User> findAll();`

002-@Insert

1 2	`@Insert("insert into user(username,address,sex,birthday)values(#{username},#{address},#{sex},#{birthday})")` `void` `saveUser(User user);`

003-@Update

1 2	`@Update("update user set username=#{username},sex=#{sex},birthday=#{birthday},address=#{address} where id=#{id}")` `void` `updateUser(User user);`

004-@Delete

1 2	`@Delete("delete from user where id=#{id} ")` `void` `deleteUser(Integer userId);`

005-查询一条用户

1 2	`@Select("select * from user where id=#{id} ")` `User findById(Integer userId);`

006-模糊查询

//@Select("select * from user where username like #{username} ")
@Select("select * from user where username like '%${value}%' ")
List<User> findUserByName(String username);

007-查询数目

1 2	`@Select("select count(*) from user ")` `int` `findTotalUser();`

008-解决数据库字段和熟悉不匹配问题

@Data
@ToString
public class User1 {
private Integer id1;
private String username1;
private Date birthday1;
private String sex1;
private String address1;
}
@Select("select * from user")
@Results(value={
@Result(id=true,column = "id",property = "id1"),
@Result(column = "username",property = "username1"),
@Result(column = "address",property = "address1"),
@Result(column = "sex",property = "sex1"),
@Result(column = "birthday",property = "birthday1")
})
List<User1> findAll();

009-解决其它方法也能用上面的注解问题

在results后面加上id 然后其它方法也引用这个id
@Results(id="userMap",value={
引用
@Select("select * from user where id=#{id} ")
@ResultMap("userMap")
User1 findById(Integer userId);

010-mybatis注解开发一对多注解
A一个账户一个用户

@Select("select * from account")
@Results(id="accountMap",value = {
@Result(id=true,column = "id",property = "id"),
@Result(column = "uid",property = "uid"),
@Result(column = "money",property = "money"),
@Result(property = "user1",column = "uid",one=@One(select="com.po.pf.repository.UserRepository1.findById",fetchType= FetchType.EAGER))
})
List<Account> findAll();
 
@Select("select * from user where id=#{id} ")
User findById(Integer userId);
 
@Data
public class Account {
private Integer id;
private Integer uid;
private Double money;
//多对一（mybatis中称之为一对一）的映射：一个账户只能属于一个用户
private User1 user1;
 
B一个用户多个账户
@Select("select * from account where uid = #{userId}")
List<Account> findAccountByUid(Integer userId);
 
@Select("select * from user")
@Results(id="userMap",value={
@Result(id=true,column = "id",property = "id1"),
@Result(column = "username",property = "username1"),
@Result(column = "address",property = "address1"),
@Result(column = "sex",property = "sex1"),
@Result(column = "birthday",property = "birthday1"),
@Result(property = "accounts",column = "id",
many = @Many(select = "com.po.pf.repository.AccountRepository1.findAccountByUid",
fetchType = FetchType.LAZY))
})
List<User1> findAll();
 
 
@Data
public class User1 {
private Integer id1;
private String username1;
private Date birthday1;
private String sex1;
private String address1;
//一对多关系映射：一个用户对应多个账户
private List<Account> accounts;