MyBatis many to one 注解

最新推荐文章于 2025-02-20 15:25:30 发布

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本文详细介绍了MyBatis框架中一对多和多对一的关联映射实现方式，通过具体的DAO接口代码示例，展示了如何使用@Select、@Result、@Many和@One注解来实现部门与员工之间的数据关联查询。

DepartmentDao 接口

public interface DepartmentDao {

    @Select("select * from t_department")
    @Results({
        @Result(column="d_id",property="id"),
        @Result(column="d_name",property="name"),
        @Result(column="d_id",property="employees",
        javaType=Set.class,many=@Many(select="getEmployeeById")
        )

    })
    List<Department> getDepartments() throws Exception;

    @Select("select * from t_employee where depart_id=#{id}")
    @Results({
        @Result(column="e_id",property="id"),
        @Result(column="e_name",property="name"),
        @Result(column="e_sex",property="sex"),
        @Result(column="e_age",property="age"),
    })
    Employee getEmployeeById(int id) throws Exception;

    @Select("select * from t_department where d_id=#{id}")
    @Results({
        @Result(column="d_id",property="id"),
        @Result(column="d_name",property="name"),
        @Result(column="d_id",property="employees",
        javaType=Set.class,many=@Many(select="getEmployeeById")
        )

    })
    Department getDepartmentById(int id) throws Exception;
}

EmployeeDao 接口

public interface EmployeeDao {

    @Select("select * from t_employee")
    @Results({
        @Result(column="e_id",property="id"),
        @Result(column="e_name",property="name"),
        @Result(column="e_age",property="age"),
        @Result(column="e_sex",property="sex"),
        @Result(column="depart_id",property="department",
        javaType=Department.class,
        one=@One(select="getDepartmentById")
        )
    })
    List<Employee> getEmployees() throws Exception;

    @Select("select * from t_department where d_id=#{id}")
    @Results({
        @Result(column="d_id",property="id"),
        @Result(column="d_name",property="name")
    })
    public Department getDepartmentById(int id) throws Exception;



    @Select("select * from t_employee where e_id=#{id}")
    @Results({
        @Result(column="e_id",property="id"),
        @Result(column="e_name",property="name"),
        @Result(column="e_age",property="age"),
        @Result(column="e_sex",property="sex"),
        @Result(column="depart_id",property="department",
        javaType=Department.class,
        one=@One(select="getDepartmentById")
        )
    })
    Employee getEmployeeById(int id) throws Exception;

}