Need help implementing a Full Outer Join in MS Access

问题

I'm having trouble getting a query to work properly in Access. I need a full outer join on dbo_cardpurchases and dbo_vendors so that all all vendors will appear in the query regardless of whether a purchase was made at that vendor. But Access doesn't support full outer joins. How else can I do this?

SELECT dbo_vendors.name, 
       Iif([fundingsourceid] = 10, [amount], "")        AS Credit, 
       Iif(( [fundingsourceid] = 2 ) 
            OR ( [fundingsourceid] = 3 ), [amount], "") AS EBT, 
       Iif([fundingsourceid] = 4, [amount], "")         AS [Match], 
       dbo_cardpurchases.updateddate, 
       dbo_markets.marketid 
FROM   (((dbo_cardpurchases 
          LEFT JOIN dbo_vendors 
                 ON dbo_cardpurchases.vendorid = dbo_vendors.vendorid) 
         LEFT JOIN dbo_cardfundings 
                ON dbo_cardpurchases.cardfundingid = 
                   dbo_cardfundings.cardfundingid) 
        INNER JOIN dbo_marketevents 
                ON dbo_cardpurchases.marketeventid = 
                   dbo_marketevents.marketeventid) 
       INNER JOIN dbo_markets 
               ON dbo_marketevents.marketid = dbo_markets.marketid 
ORDER  BY dbo_vendors.name;

回答1:

As mentioned in the Wikipedia article on joins here, for sample tables

[employee]

LastName    DepartmentID
----------  ------------
Heisenberg            33
Jones                 33
Rafferty              31
Robinson              34
Smith                 34
Williams            NULL

and [department]

DepartmentID  DepartmentName
------------  --------------
          31  Sales         
          33  Engineering   
          34  Clerical      
          35  Marketing

the full outer join

SELECT *
FROM employee FULL OUTER JOIN department
    ON employee.DepartmentID = department.DepartmentID;

can be emulated using a UNION ALL of three SELECT statements. So, in Access you could do

SELECT dbo_employee.LastName, dbo_employee.DepartmentID,
       dbo_department.DepartmentName, dbo_department.DepartmentID
FROM dbo_employee
INNER JOIN dbo_department ON dbo_employee.DepartmentID = dbo_department.DepartmentID

UNION ALL

SELECT dbo_employee.LastName, dbo_employee.DepartmentID,
       NULL, NULL
FROM dbo_employee
WHERE NOT EXISTS (
    SELECT * FROM dbo_department
             WHERE dbo_employee.DepartmentID = dbo_department.DepartmentID)

UNION ALL

SELECT NULL, NULL,
       dbo_department.DepartmentName, dbo_department.DepartmentID
FROM dbo_department
WHERE NOT EXISTS (
    SELECT * FROM dbo_employee
             WHERE dbo_employee.DepartmentID = dbo_department.DepartmentID)

However, since you are using linked tables into SQL Server you can just use an Access pass-through query and perform a "real" FULL OUTER JOIN using T-SQL:

Pass-through queries always produce recordsets that are not updateable, but a native Access query against linked tables that uses UNION ALL is going to produce a recordset that is not updatable anyway, so why not take advantage of the speed and simplicity of just using SQL Server to run the query?

来源：https://stackoverflow.com/questions/26511927/need-help-implementing-a-full-outer-join-in-ms-access

标签

sql-server

ms-access

outer-join