Question

我在这里有点迷失......

我有几个表格，我想从Unit，Building，Owner和Picture中提取统一记录。

到目前为止，这是我的查询：

SELECT building.`Street_Address`
    , building.`Building_Name`
    , building.`Building_Type`
    , CONCAT(building.`Cross_Street_1`, ' & ', building.`Cross_Street_2`) Cross_Streets
    , building.`Cross_Street_1`
    , building.`Cross_Street_2`
    , building.`Access` Building_Access
    , owner.`Company_Name`
    , owner.`Contact_Or_Reference`
    , owner.`Landlord_Phone`
    , picture.`Path_To_Picture_On_Server`
    , picture.`Picture_Category`
    , unit.`Apartment_Number`
    , unit.`Unit_Size_Number` Size
    , unit.`Is_Doorman`
    , unit.`Is_Furnished`
    , unit.`Is_Elevator`
    , unit.`Is_Pets`
    , unit.`Is_OutdoorSpace`
    , unit.`Rent_Price`
    , unit.`Baths`
    , unit.`Access` Unit_Access
    , unit.`fourd_id`
    , unit.`Updated_Date`
    , unit.`Occupancy_Date`
    , unit.`Term`
    , unit.`Incentives`
    , unit.`Info_OutdoorSpace`
    , unit.`List_Date`
    , zone.`Description`
FROM 4D_Units unit
JOIN 4D_Building building
    ON unit.`BUILDING_RecID` = building.`fourd_id`
JOIN 4D_Zones zone
    ON building.`ZONES_RecID` = zone.`fourd_id`
LEFT JOIN 4D_Owners owner
    ON unit.`OWNER_RecID` = owner.`fourd_id`
LEFT JOIN 4D_Building_Picts picture
    ON (building.`fourd_id` = picture.`BUILDING_RecID` AND picture.`Picture_Category` = 'Front')
WHERE unit.`id` = 49901

这样可以正常工作，除了返回记录只有记录中的“前”图像（如果存在）。我的问题是，有几种不同类型的照片可以与返回记录相关联，包括“全景”，“内部”和“平面图”......所有这些都是picture.Picture_Category的不同可能值。

有没有办法在返回的集合中返回这些值（如果它们存在，如上所述）而不进行单独的查询？我希望返回的集合包含picture.Picture_Category的所有四个可能选项的别名值（如果存在）：'Front'，'Panorama'，'Interior'，＆amp; '平面图'（与其关联的唯一picture.Path_To_Picture_On_Server）。

这有意义吗？

Answer 1

如果我理解正确，您希望结果集中有4组图片列 - 其中一列是4个类别？现在你只有一个在前面，对吧？

您可以使用不同的别名和不同的join子句多次加入同一个表。只需加入4D_Building_Picts 4次，每张图片一次。

select 
    --whatever
    , pic_front.`Path_To_Picture_On_Server` AS Front_Path_To_Picture_On_Server
    , pic_panorama.`Path_To_Picture_On_Server` AS Panorama_Path_To_Picture_On_Server
    , pic_interior.`Path_To_Picture_On_Server` AS Interior_Path_To_Picture_On_Server
    , pic_floorplan.`Path_To_Picture_On_Server` AS Floorplan_Path_To_Picture_On_Server
    --whatever
FROM 4D_Units unit
JOIN 4D_Building building
    ON unit.`BUILDING_RecID` = building.`fourd_id`
JOIN 4D_Zones zone
    ON building.`ZONES_RecID` = zone.`fourd_id`
LEFT JOIN 4D_Owners owner
    ON unit.`OWNER_RecID` = owner.`fourd_id`
LEFT JOIN 4D_Building_Picts pic_front
    ON (building.`fourd_id` = pic_front.`BUILDING_RecID` AND pic_front.`Picture_Category` = 'Front')
LEFT JOIN 4D_Building_Picts pic_panorama
    ON (building.`fourd_id` = pic_panorama.`BUILDING_RecID` AND pic_panorama.`Picture_Category` = 'Panorama')
LEFT JOIN 4D_Building_Picts pic_interior
    ON (building.`fourd_id` = pic_interior.`BUILDING_RecID` AND pic_interior.`Picture_Category` = 'Interior')
LEFT JOIN 4D_Building_Picts pic_floorplan
    ON (building.`fourd_id` = pic_floorplan.`BUILDING_RecID` AND pic_floorplan.`Picture_Category` = 'Floorplan')
WHERE unit.`id` = 49901

Answer 2

我认为你想要合并功能。它需要多个字段，并返回其中第一个非空字段。如下所示：

Select
  Coalesce(A.Panorama, A.Interior, A.Floorplan, '') as ImagePath
From
  Table A

你只能以这种方式得到一个值，这可能实际上并不是你所追求的。如果你想要所有这些，我建议使用相关的子查询，如下所示：

Select
  (Select P.Path_To_Picture From 4D_Building_Picts P where P.Building_RecID = B.fourd_Id And P.Picture_Category = 'Front') as Front_Pic,
  (Select P.Path_To_Picture From 4D_Building_Picts P where P.Building_RecID = B.fourd_Id And P.Picture_Category = 'Panorama') as Panamora_Pic,
  (Select P.Path_To_Picture From 4D_Building_Picts P where P.Building_RecID = B.fourd_Id And P.Picture_Category = 'FloorPlan') as FloorPlan_Pic,
  ...
From
  4D_Building B

SQL子选择为字段？

2 个答案: