Question

This is related to my previous question More than 1 Left joins in MSAccess

The problem is that I have 3 left joins followed by an AND operator to check 1 condition.

If I run, then I am getting an error “Join Expression not supported”.

The query goes like this:

SELECT * FROM(( EMPLOYEE AS E  LEFT JOIN DEPARTMENT AS D ON E.EID=D.EID)
                 LEFT JOIN MANAGERS M ON D.DID=M.DID)
             LEFT JOIN MANAGERDETAILS MD  ON M.MDID=MD.MDID
 **AND E.ENO=MD.ENO**

If I take out AND part, it works fine.

Any idea?

Answer 1

The way I would write this would be:

SELECT EDM.*, MANAGERDETAILS.*
FROM (
    SELECT ED.*, MANAGERS.*
    FROM (
        SELECT EMPLOYEE.*, DEPARTMENT.*
        FROM EMPLOYEE
        LEFT JOIN DEPARTMENT
        ON EMPLOYEE.EID = DEPARTMENT.EID
    ) AS ED
    LEFT JOIN MANAGERS
    ON ED.DID = MANAGERS.DID
) AS EDM
LEFT JOIN MANAGERDETAILS
ON EDM.MDID = MANAGERDETAILS.MDID
    AND EDM.ENO = MANAGERDETAILS.ENO

Basically, you join tables one at a time and alias the result that you can then use for the next join.

You can achieve arbitrarily complex Left joins in Access only by aliasing smaller subsets.
Your double join clause probably doesn’t work because one of its members refers to a deeper resultset than the one that’s visible at that level of the query.