mybatis中union all与union的用法

1.需求分析

  很多情况下，我们会遇到类似的需求：混合型的列表再进行分类；这种情况，可以考虑java逻辑层面两个甚至更多的list相加，然后最后进行排序，但是一旦进行分页，排序可能就混乱了，这个笔者建议直接在sql里面union all多个结果集，然后对整体进行排序

2.UNION ALL 与UNION的区别

Union：对两个结果集进行并集操作，不包括重复行，同时进行默认规则的排序；

Union All：对两个结果集进行并集操作，包括重复行，不进行排序；

union all的效率比union快的多，如果可以确认合并的结果集中不包含重复数据的话，那么就用union all

3.实现方案

sql代码如下

id="getNightOptimizationOwnerServiceListByPasser" resultMap="OwnerResultMap" parameterType="java.util.Map">
 SELECT
  union_owner.*
 FROM
  (SELECT
  vehicle.vehicle_id,
  vehicle.vehicle_type,
  sys.user_mobile,
  sys.user_nickname,
  car.service_id,
  car.user_id,
  car.pin_service_code,
  car.pin_leave_words,
  car.pin_start_point,
  car.pin_end_point,
  car.pin_start_latitude,
  car.pin_start_longitude,
  car.pin_end_latitude,
  car.pin_end_longitude,
  car.pin_total_account,
  car.pin_service_account,
  car.pin_single_lose_account AS pin_lose_account,
  car.owner_has_seats,
  car.leave_off_time,
  car.pin_total_distance,
  car.pin_service_kinds,
  car.pin_create_time
  FROM
  yivi_pin_car_service car
  INNER JOIN yivi_vehicle_info vehicle ON car.user_id = vehicle.user_id
  AND vehicle.vehicle_identity_status = 1
  INNER JOIN yivi_sys_user sys ON sys.user_id = car.user_id
  AND sys.user_vehicle_identity = 1
  WHERE
  car.pin_publish_role = 1
  AND car.service_enable = 1
  AND car.service_status = 1
  AND car.pin_is_visible = 1
  AND car.pin_time_out = 0
  test="pinServiceKinds != null and pinServiceKinds != '' ">AND car.pin_service_kinds = #{pinServiceKinds}
  
  test="pinServiceKinds != null and pinServiceKinds != 3 and startLatitude != null and startLongitude != null and endLatitude != null and endLongitude != null"> 
    AND ROUND(
    6378.138 * 2 * asin(
    sqrt(
    pow(
    sin(
    (
    car.pin_start_latitude * pi() / 180 - #{startLatitude} * pi() / 180
    ) / 2
    ),
    2
    ) + cos(car.pin_start_latitude * pi() / 180) * cos(#{startLatitude} * pi() / 180) * pow(
    sin(
    (
    car.pin_start_longitude * pi() / 180 - #{startLongitude} * pi() / 180
    ) / 2
    ),
    2
    )
    )
    )
    ,
    2
    ) <= 100
    AND ROUND (
    6378.138 * 2 * asin(
    sqrt(
    pow(
    sin(
    (
    car.pin_end_latitude * pi() / 180 - #{endLatitude} * pi() / 180
    ) / 2
    ),
    2
    ) + cos(car.pin_end_latitude * pi() / 180) * cos(#{endLatitude} * pi() / 180) * pow(
    sin(
    (
    car.pin_end_longitude * pi() / 180 - #{endLongitude} * pi() / 180
    ) / 2
    ),
    2
    )
    )
    )
    ,
    2
    ) <= 100
  
  test="pinServiceKinds == 3 ">
    test="startLatitude != null and startLongitude != null">
      AND ROUND(
      6378.138 * 2 * asin(
      sqrt(
      pow
      (
      sin(
      (
      car.pin_start_latitude * pi() / 180 - #{startLatitude} * pi() / 180
      ) / 2
      ),
      2
      ) + cos(car.pin_start_latitude * pi() / 180) * cos(#{startLatitude} * pi() / 180) * pow(
      sin(
      (
      car.pin_start_longitude * pi() / 180 - #{startLongitude} * pi() / 180
      ) / 2
      ),
      2
      )
      )
      )
      ,
      2
      ) <= 40
    

    test="endLatitude != null and endLongitude != null ">
    AND ROUND(
    6378.138 * 2 * asin(
    sqrt(
    pow(
    sin(
    (
    car.pin_end_latitude * pi() / 180 - #{endLatitude} * pi() / 180
    ) / 2
    ),
    2
    ) + cos(car.pin_end_latitude * pi() / 180) * cos(#{endLatitude} * pi() / 180) * pow(
    sin(
    (
    car.pin_end_longitude * pi() / 180 - #{endLongitude} * pi() / 180
    ) / 2
    ),
    2
    )
    )
    )
    ,
    2
    ) <= 40
    
  
  test="leaveOffTime != null ">
    and date_format(car.leave_off_time,'%Y-%m-%d')= date_format(#{leaveOffTime},'%Y-%m-%d')
  
  test="leftLeaveOffTime!= null ">
    and UNIX_TIMESTAMP(car. leave_off_time) >= UNIX_TIMESTAMP(date_format(#{leftLeaveOffTime},'%Y-%m-%d %H:%i'))
  
  test="rightLeaveOffTime!= null ">
    and UNIX_TIMESTAMP(car. leave_off_time) <= UNIX_TIMESTAMP(date_format(#{rightLeaveOffTime},'%Y-%m-%d %H:%i'))
  
  test="vehicleType != null and vehicleType != 0">
    and vehicle.vehicle_type = #{vehicleType}
  

  test="pinServiceKinds != null and pinServiceKinds == 1">
    UNION
    SELECT
    vehicle.vehicle_id,
    vehicle.vehicle_type,
    sys.user_mobile,
    sys.user_nickname,
    car.service_id,
    car.user_id,
    car.pin_service_code,
    car.pin_leave_words,
    car.pin_start_point,
    car.pin_end_point,
    car.pin_start_latitude,
    car.pin_start_longitude,
    car.pin_end_latitude,
    car.pin_end_longitude,
    car.pin_total_account,
    car.pin_service_account,
    car.pin_single_lose_account AS pin_lose_account,
    car.owner_has_seats,
    car.leave_off_time,
    car.pin_total_distance,
    car.pin_service_kinds,
    car.pin_create_time
    FROM
    yivi_pin_car_service car
    INNER JOIN yivi_vehicle_info vehicle ON car.user_id = vehicle.user_id
    AND vehicle.vehicle_identity_status = 1
    INNER JOIN yivi_sys_user sys ON sys.user_id = car.user_id
    AND sys.user_vehicle_identity = 1
    WHERE
    car.pin_publish_role = 1
    AND car.service_enable = 1
    AND car.service_status = 1
    AND car.pin_is_visible = 1
    AND car.pin_time_out = 0
    AND car.pin_service_kinds = 2
    AND car.pin_total_distance > 100
  

  test="pinServiceKinds != null and pinServiceKinds == 3">
    UNION
    SELECT
    vehicle.vehicle_id,
    vehicle.vehicle_type,
    sys.user_mobile,
    sys.user_nickname,
    car.service_id,
    car.user_id,
    car.pin_service_code,
    car.pin_leave_words,
    car.pin_start_point,
    car.pin_end_point,
    car.pin_start_latitude,
    car.pin_start_longitude,
    car.pin_end_latitude,
    car.pin_end_longitude,
    car.pin_total_account,
    car.pin_service_account,
    car.pin_single_lose_account AS pin_lose_account,
    car.owner_has_seats,
    car.leave_off_time,
    car.pin_total_distance,
    car.pin_service_kinds,
    car.pin_create_time
    FROM
    yivi_pin_car_service car
    INNER JOIN yivi_vehicle_info vehicle ON car.user_id = vehicle.user_id
    AND vehicle.vehicle_identity_status = 1
    INNER JOIN yivi_sys_user sys ON sys.user_id = car.user_id
    AND sys.user_vehicle_identity = 1
    WHERE
    car.pin_publish_role = 1
    AND car.service_enable = 1
    AND car.service_status = 1
    AND car.pin_is_visible = 1
    AND car.pin_time_out = 0
    AND car.pin_service_kinds = 2
    AND car.pin_total_distance < 100
  

  ) union_owner
  ORDER BY union_owner.leave_off_time ASC 
  LIMIT ${pageNo},
  ${pageSize}

4.使用注意事项

①.所有查询中的列数和列的顺序必须相同；

②.对应项的数据类型必须兼容；

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