从 5 个表中获取数据

Question

i have 5 tables contains city information (Unite contain (but not always) sub unites - sub unites contain (but not always) building - and building contain (but not always) rooms

1-Unites: includes columns:

Id (PK)

UniteName

....

2- SubUnites: includes columns:

ID (PK)

Name

UniteId(FK for ID in Unites table Table)- Note (not all unite contain sub unite) ....

3- Building: includes columns:

ID (PK)

Name

SubUniteId (FK for ID in SubUnites Table)- Note (not all unite sub unite contain buildings) ...

4- Rooms: includes columns :

ID (PK)

Name

BuildingId (FK for ID in Building Table)- Note (not all building contain rooms) ....

5- Orders : includes columns:

ID

AreaId (which may be (ID column from Unite table) or (ID column from SubUnites table) or (ID column from Building table) or (ID column from Rooms table)

i can make order for for any of them by its ID

question : how i can make sql select query to get orders for any of them with full information .. which mean if i get orders for a specif room i need to know in which building and in which sub unite and in which unite and if i get orders for a specific building i need to know in which sub untes and in which unites an so on- with out duplicating data

i tried many queries but not working

any help

Answer 1

SELECT A.ID as unitid,A.Unitname as unitname,B.id as subuniteid,B.Name as subunitname,c.ID as buildingid,C.Name as buildingname,D.id as roomid,D.name as roomname,e.id as orderid,e.areaid
from
UniT A JOIN Subunit B
on A.Id=B.UnitId
Join Building c
on B.ID=C.Subunitid
Join Room D
ON C.ID=D.buildingid
Join Orders E 
on E.Id=A.Id

Answer 2

So it looks like you are trying to have a table [Orders] which is going to link/ relate to potentially 4 other tables via the [AreaId] column.

The problem is you haven't provided either a column to specify which table you are relating to for each particular order record.

Split the [Orders] table into 4 separate Orders tables with an order for each or provide a means, ie [UniteOrders], [SubUniteOrders], etc. Making each a one-unit to many orders relationship

Then if you want all orders, you could do a Union query to pull from all the tables

Another option would be to use GUIDs as the IDs and then you could store them in the [AreaId] and be certain to a high degree there would be no duplicates.

SQL Server doc on GUID type:

https://msdn.microsoft.com/en-us/library/ms187942.aspx

Answer 3

Ill give this a shot with out having access to the data. Please let me know if this is what you're trying to accomplish.

Select 
  U.ID
, U.NAME
, U.UniteName
, O_FROM_U.*
, SU.ID
, SU.NAME
, SU.UniteID
, O_FROM_SU.*
, B.ID
, B.Name
, B.SubUniteID
, O_FROM_B.*
, R.ID
, R.Name
, R.BuildingID
, O_FROM_R.*

FROM
Unites U
LEFT OUTER JOIN SubUnites SU        ON SU.UNITEID = U.ID
LEFT OUTER JOIN Building B          ON B.SubUniteID = SU.ID
LEFT OUTER JOIN Rooms R             ON R.BuildingID = B.ID

LEFT OUTER JOIN ORDERS O_FROM_U     ON U.ID = O_FROM_U.AreaID
LEFT OUTER JOIN ORDERS O_FROM_SU    ON SU.ID = O_FROM_SU.AreaID
LEFT OUTER JOIN ORDERS O_FROM_B     ON B.ID = O_FROM_B.AreaID
LEFT OUTER JOIN ORDERS O_FROM_R     ON R.ID = O_FROM_R.AreaID