在两个不同的列中组合具有ID的联接表的方法？

Question

I've been trying to figure out how to join a table to other tables that I've joined but the way the tables are set-up, EventTable has the OrderID only if certain events happen. Otherwise it's Null.

EventTable

EventID EventName  OrderID DateTS
1       Rec        1       date1
2       Track      NULL    date2
3       Run        NULL    date3

EventItemTable

 EventID    Column2    OrderID
    1       Other      1
    2       stuff      2
    3       beer       3

OrderTable

OrderID         orderRef   ProdID
        1       1234       1
        2       1233       1
        3       1232       3

Now I've been trying to get all the Event rows which has all of the events that I'm looking for. What I need to be able to do is be able to allow users to use Tableau which will filter the orderRef column to show all the events that occurred.

I'm pretty new to SQL queries and the per row logic I'm thinking would be if statement but don't know how it would work in SQL.

SELECT OrderTable.orderRef, EventTable.DateTS, EventTable.EventName

If EventTable.OrderID column isNull, then          

FROM EventItemTable  
  join EventItemTable ON EventItemTable.OrderID = EventTable.OrderID
  join OrderTable ON OrderTable.OrderID = EventItemTable.OrderID

ELSE

 FROM EventItemTable 
  left join OrderTable ON OrderTable.OrderID = EventTable.OrderID

In my mind, I would think that the orderRef would then be populated in the entire table and have no nulls or be filter out. I would still be able to have all the other columns but with the else condition the rows would just be populated with NULL. I've been looking at subqueries and other functions to try but not seeing anything that seems to be able to do this. I'm using a Microsoft SQL 2005 (I believe)

EDIT

This is what I ended up with that got all the OrderID in one column to join with @AlexJohnson suggestion. My issue now is that a couple have duplicate manufacturingEventID in the rows per order reference. Not sure if the ISNULL is causing that issue

SELECT met.met_ManufacturingEventID
        ,met.met_OrderID
        ,ori.ori_OrderID
        ,mfi.mfi_OrderID
        ,mfi.mfi_LastEvent
        ,mfi.mfi_RunNumber
        ,mfi.mfi_InputOrder
        ,meo.meo_ManufacturingOperationName
        ,mes.mes_ManufacturingStationName as StationName
        ,mes.mes_StationStatusName as StationStatus
      ,met.met_EventDate as EventDate
--      ,oie.oie_EventDate
        ,met.met_ToothID
      ,met.met_Comment as metComment
      ,met.met_ManufacturingOrderNumber
--      ,ISNULL(mfi.mfi_OrderID,met.met_OrderID) as OrderID
        ,ord.ord_OrderReference as OrderRef


  FROM [dbo].[ManufacturingEvents] met
  LEFT JOIN [dbo].[ManufacturingEventOrderItems] mfi
      ON mfi.mfi_ManufacturingEventID = met.met_ManufacturingEventID
  LEFT JOIN [dbo].[OrderItems] ori
      ON ori.ori_OrderItemID = mfi.mfi_OrderItemID
  LEFT JOIN [AtlantisProductionSystem_Prod_US].[dbo].[Orders] ord
      ON ord.ord_OrderID = ISNULL(mfi.mfi_OrderID,met.met_OrderID)
  LEFT JOIN dbo.ManufacturingStations mes
      ON mes.mes_ManufacturingStationID = met.met_ManufacturingStationID
  JOIN dbo.ManufacturingOperations meo
      ON meo.meo_ManufacturingOperationID = mes.mes_ManufacturingOperationID

Answer 1

Give this a shot:

SELECT ot.orderRef, et.DateTS, et.EventName
FROM OrderTable ot
JOIN EventItemTable eit
  ON eit.OrderID = ot.OrderID
LEFT JOIN EventTable et
  ON et.OrderID = ot.OrderID

You will still probably want to tweak this because if the EventTable OrderID is null, the information returned may not be useful.

You can use:

SELECT ot.orderRef, et.DateTS, ISNULL(et.EventName, eit.Column2)

Or something similar.

I'm not sure if EventTable and EventItemTable have any other relationship besides OrderID, but if we could join them on EventID you could get much better results:

SELECT ot.orderRef, et.DateTS, et.EventName
FROM EventTable et
JOIN EventItemTable eit
  ON et.EventID = eit.EventID
JOIN OrderTable ot
  ON eit.OrderID = ot.OrderID