Hi!

Correct, but not for all versions.

>>Yes, now its much clear. Following is completed qyery:
>>
>>

>>SELECT RR.ID as Request, RR.EmployeeID as Employee,
>>      RR.CourseID as Course, PP.PrerequisiteID as Prereq,
>>      iif(IsNull(Completion.StatusID,0,Completion.StatusID)) as Completed
>>  FROM
>>    (Requests as RR
>>      INNER JOIN Courses as CC
>>        ON RR.CourseID = CC.ID
>>      LEFT JOIN Prerequisites PP
>>        ON PP.CourseID = CC.ID)
>>    LEFT JOIN Requests as Completion
>>      ON Completion.CourseID = PP.CourseID AND Completion.EmployeeID = Requests.EmployeeID
>>

>>
>>HTH.
>

---

>You can use NVL function to convert NULL value
>

>NVL(Completion.StatusID,0) as Completed
>instead of
>iif(IsNull(Completion.StatusID,0,Completion.StatusID)) as Completed
>