数据持久层之——MyBatis

     一.对myibatis的认知

         我也是刚接触ibatis的，作为数据持久层的框架相比于ibatis我对于hibernate更加的熟悉。 先说说ibatis与hibernate的区别吧。两者都是数据持久层的框架用来表示ORM(对象的关系映射)。而hibernate是一款全自动的ORM，提供了从POJO到数据库表的全套映射机制。程序员往往只需定义好了POJO 到数据库表的映射关系，即可通过 Hibernate 提供的方法完成持久层操作。程序员甚至不需要对 SQL 的熟练掌握，Hibernate 会根据制定的存储逻辑，自动生成对应的 SQL 并调用 JDBC 接口加以执行。到数据库表的全套映射机制，ibatis是一款半自动的ORM，batis 的着力点，则在于POJO 与 SQL之间的映射关系。也就是说，ibatis并不会为程序员在运行期自动生成 SQL 执行。具体的 SQL 需要程序员编写，然后通过映射配置文件，将SQL所需的参数，以及返回的结果字段映射到指定 POJO。

  二.ibatis的SQL语句的书写

    1.这是xml文件的DTD约束：

       

   2.对应dao层和javaBEAN

 

    3.对应于数据库表的字段名和数据类型

   
   
   
   
   
   
   
   
   
   
   
   
   
   
   
 
 
    fake_id, create_datetime, update_datetime, employee_uuid, delete_at, approval_uuid, 
    approval_title, approval_type, approval_status, missions_status, missions_title, 
    missions_uuid, missions_creator_uuid, approval_creator_uuid, event_todo_uuid
 

     4.查询语句
 
    select 
   
    from event_todo_info
    where fake_id = #{fakeId,jdbcType=INTEGER}
 
 
    select 
   
    from event_todo_info
    where approval_uuid = #{approvalUuid,jdbcType=VARCHAR}
 
 
    select 
   
    from event_todo_info
    where missions_uuid = #{missionsUuid,jdbcType=VARCHAR} 

    模糊查询
 

 
    select
     
    from event_todo_info
    where delete_at is null and employee_uuid like CONCAT(CONCAT('%' #{employee_uuid,jdbcType=VARCHAR}),'%') limit #{start},#{limit}
 
 
    select count(*) from event_todo_info where delete_at is null
 
 
   select 
   
   from event_todo_info
   where event_todo_uuid = #{eventTodoUuid,jdbcType=VARCHAR} and delete_at is null
 
 
    select  
     
    from event_todo_info
    where delete_at is null and employee_uuid like CONCAT(CONCAT( #{condition,jdbcType=VARCHAR}),'%')
    or approval_title like CONCAT(CONCAT('%' , #{condition,jdbcType=VARCHAR}),'%')
    or missions_title like CONCAT(CONCAT('%' , #{condition,jdbcType=VARCHAR}),'%') limit #{start},#{limit}
 

    删除语句
 
    delete from event_todo_info
    where fake_id = #{fakeId,jdbcType=INTEGER}
 

     插入语句
 
    insert into event_todo_info (fake_id, create_datetime, update_datetime, 
      employee_uuid, delete_at, approval_uuid, 
      approval_title, approval_type, approval_status, 
      missions_status, missions_title, missions_uuid, 
      missions_creator_uuid, approval_creator_uuid, 
      event_todo_uuid)
    values (#{fakeId,jdbcType=INTEGER}, #{createDatetime,jdbcType=TIMESTAMP}, #{updateDatetime,jdbcType=TIMESTAMP}, 
      #{employeeUuid,jdbcType=VARCHAR}, #{deleteAt,jdbcType=VARCHAR}, #{approvalUuid,jdbcType=VARCHAR}, 
      #{approvalTitle,jdbcType=VARCHAR}, #{approvalType,jdbcType=VARCHAR}, #{approvalStatus,jdbcType=VARCHAR}, 
      #{missionsStatus,jdbcType=VARCHAR}, #{missionsTitle,jdbcType=VARCHAR}, #{missionsUuid,jdbcType=VARCHAR}, 
      #{missionsCreatorUuid,jdbcType=VARCHAR}, #{approvalCreatorUuid,jdbcType=VARCHAR}, 
      #{eventTodoUuid,jdbcType=VARCHAR})
 
 
    insert into event_todo_info
   
     
        fake_id,
     
     
        create_datetime,
     
     
        update_datetime,
     
     
        employee_uuid,
     
     
        delete_at,
     
     
        approval_uuid,
     
     
        approval_title,
     
     
        approval_type,
     
     
        approval_status,
     
     
        missions_status,
     
     
        missions_title,
     
     
        missions_uuid,
     
     
        missions_creator_uuid,
     
     
        approval_creator_uuid,
     
     
        event_todo_uuid,
     
   
   
     
        #{fakeId,jdbcType=INTEGER},
     
     
        #{createDatetime,jdbcType=TIMESTAMP},
     
     
        #{updateDatetime,jdbcType=TIMESTAMP},
     
     
        #{employeeUuid,jdbcType=VARCHAR},
     
     
        #{deleteAt,jdbcType=VARCHAR},
     
     
        #{approvalUuid,jdbcType=VARCHAR},
     
     
        #{approvalTitle,jdbcType=VARCHAR},
     
     
        #{approvalType,jdbcType=VARCHAR},
     
     
        #{approvalStatus,jdbcType=VARCHAR},
     
     
        #{missionsStatus,jdbcType=VARCHAR},
     
     
        #{missionsTitle,jdbcType=VARCHAR},
     
     
        #{missionsUuid,jdbcType=VARCHAR},
     
     
        #{missionsCreatorUuid,jdbcType=VARCHAR},
     
     
        #{approvalCreatorUuid,jdbcType=VARCHAR},
     
     
        #{eventTodoUuid,jdbcType=VARCHAR},
     
   
 

      更新语句
 
    update event_todo_info
   
     
        create_datetime = #{createDatetime,jdbcType=TIMESTAMP},
     
     
        update_datetime = #{updateDatetime,jdbcType=TIMESTAMP},
     
     
        employee_uuid = #{employeeUuid,jdbcType=VARCHAR},
     
     
        delete_at = #{deleteAt,jdbcType=VARCHAR},
     
     
        approval_uuid = #{approvalUuid,jdbcType=VARCHAR},
     
     
        approval_title = #{approvalTitle,jdbcType=VARCHAR},
     
     
        approval_type = #{approvalType,jdbcType=VARCHAR},
     
     
        approval_status = #{approvalStatus,jdbcType=VARCHAR},
     
     
        missions_status = #{missionsStatus,jdbcType=VARCHAR},
     
     
        missions_title = #{missionsTitle,jdbcType=VARCHAR},
     
     
        missions_uuid = #{missionsUuid,jdbcType=VARCHAR},
     
     
        missions_creator_uuid = #{missionsCreatorUuid,jdbcType=VARCHAR},
     
     
        approval_creator_uuid = #{approvalCreatorUuid,jdbcType=VARCHAR},
     
     
        event_todo_uuid = #{eventTodoUuid,jdbcType=VARCHAR},
     
   
    where fake_id = #{fakeId,jdbcType=INTEGER}
 
 
    update event_todo_info
    set create_datetime = #{createDatetime,jdbcType=TIMESTAMP},
      update_datetime = #{updateDatetime,jdbcType=TIMESTAMP},
      employee_uuid = #{employeeUuid,jdbcType=VARCHAR},
      delete_at = #{deleteAt,jdbcType=VARCHAR},
      approval_uuid = #{approvalUuid,jdbcType=VARCHAR},
      approval_title = #{approvalTitle,jdbcType=VARCHAR},
      approval_type = #{approvalType,jdbcType=VARCHAR},
      approval_status = #{approvalStatus,jdbcType=VARCHAR},
      missions_status = #{missionsStatus,jdbcType=VARCHAR},
      missions_title = #{missionsTitle,jdbcType=VARCHAR},
      missions_uuid = #{missionsUuid,jdbcType=VARCHAR},
      missions_creator_uuid = #{missionsCreatorUuid,jdbcType=VARCHAR},
      approval_creator_uuid = #{approvalCreatorUuid,jdbcType=VARCHAR},
      event_todo_uuid = #{eventTodoUuid,jdbcType=VARCHAR}
    where fake_id = #{fakeId,jdbcType=INTEGER}