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Null values in my table are causing problems in my join query

Posted on 2011-03-08

1 solution

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Last Modified: 2013-11-27

Hello,
I'm joining multiple tables to create a report. It works fine unless I run into NULL values in the join statement. What can I do to fix this? Below is my query.

 strQuery = "SELECT Requests.*, RequestTypes.RequestTypeID, RequestType, [Approved/Unapproved].ID, [Approved/Unapproved].[Approved/Unapproved], " & _
                    "[Type of Leave].ID , TypeOfLeave " & _
                    "FROM Requests, RequestTypes, [Approved/Unapproved], [Type of Leave] " & _
                    "WHERE ((Requests.StartDate Between #" & strStartDate & "#" & " And #" & strEndDate & "#" & _
                    "OR Requests.EndDate Between #" & strStartDate & "#" & " And #" & strEndDate & "#)" & _
                    "AND Requests.Department = " & "'" & strDepartment & "'" & ")" & _
                    "AND Requests.RequestTypeID = RequestTypes.RequestTypeID " & _
                    "AND CInt(Requests.[Approved/Unapproved]) = [Approved/Unapproved].ID " & _
                    "AND CInt(Requests.[Request Type]) = [Type of Leave].ID " & _
                    "ORDER BY RequestID"

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What's causing errors is when CInt(Requests.[Approved/Unapproved]) is NULL (this is a text field in my table). And when CInt(Requests.[Request Type]) is NULL (this is also a text field in my table).

Comment

Question by:AronMcD

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12 Comments

LVL 12

Expert Comment

by:Nathan Riley

ID: 350716512011-03-08

What fields and I can rewrite it for you, unless you know how do this.

isnull(fieldname,' ')

LVL 15

Expert Comment

by:derekkromm

ID: 350716972011-03-08

In access, its actually Nz()

so if this line was giving you trouble:

"AND Requests.Department = " & "'" & strDepartment & "'" & ")" & _

change it to this:

"AND Nz(Requests.Department, '') = " & "'" & strDepartment & "'" & ")" & _

LVL 15

Expert Comment

by:derekkromm

ID: 350716992011-03-08

MS article on Nz:

http://office.microsoft.com/en-us/access-help/nz-function-HA001228890.aspx

Author Comment

by:AronMcD

ID: 350717112011-03-08

Gallitin,
Thank you for the quick response. The fields that are causing me problems are in BOLD below. The Requests.RequestTypeID is a Numeric field in my table. I'm not sure if that will cause problems using isnull or not. I'm not so much concerned about that though as that field is rarely left null. Let me know if you need more. Thanks.

strQuery = "SELECT Requests.*, RequestTypes.RequestTypeID, RequestType, [Approved/Unapproved].ID, [Approved/Unapproved].[Approved/Unapproved], " & _
"[Type of Leave].ID , TypeOfLeave " & _
"FROM Requests, RequestTypes, [Approved/Unapproved], [Type of Leave] " & _
"WHERE ((Requests.StartDate Between #" & strStartDate & "#" & " And #" & strEndDate & "#" & _
"OR Requests.EndDate Between #" & strStartDate & "#" & " And #" & strEndDate & "#)" & _
"AND Requests.Department = " & "'" & strDepartment & "'" & ")" & _
"AND Requests.RequestTypeID = RequestTypes.RequestTypeID " & _
"AND CInt(Requests.[Approved/Unapproved]) = [Approved/Unapproved].ID " & _
"AND CInt(Requests.[Request Type]) = [Type of Leave].ID " & _
"ORDER BY RequestID"

LVL 15

Expert Comment

by:derekkromm

ID: 350717242011-03-08

"AND Nz(Requests.RequestTypeID, 0) = RequestTypes.RequestTypeID " & _
"AND Nz(CInt(Requests.[Approved/Unapproved]), 0) = [Approved/Unapproved].ID " & _
"AND Nz(CInt(Requests.[Request Type]), 0) = [Type of Leave].ID " & _

LVL 12

Expert Comment

by:Nathan Riley

ID: 350717372011-03-08

This is MS SQL

strQuery = "SELECT Requests.*, RequestTypes.RequestTypeID, RequestType, [Approved/Unapproved].ID, [Approved/Unapproved].[Approved/Unapproved], " & _
                    "[Type of Leave].ID , TypeOfLeave " & _
                    "FROM Requests, RequestTypes, [Approved/Unapproved], [Type of Leave] " & _
                    "WHERE ((Requests.StartDate Between #" & strStartDate & "#" & " And #" & strEndDate & "#" & _
                    "OR Requests.EndDate Between #" & strStartDate & "#" & " And #" & strEndDate & "#)" & _
                    "AND Requests.Department = " & "'" & strDepartment & "'" & ")" & _
                    "AND isnull(Requests.RequestTypeID,0) = RequestTypes.RequestTypeID " & _
                    "AND CInt(isnull(Requests.[Approved/Unapproved],0)) = [Approved/Unapproved].ID " & _
                    "AND CInt(isnull(Requests.[Request Type],0)) = [Type of Leave].ID " & _
                    "ORDER BY RequestID"

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LVL 19

Expert Comment

by:MINDSUPERB

ID: 350717382011-03-08

Try to use the Nz function:

CInt(Nz(Requests.[Approved/Unapproved],0))

CInt(Nz(Requests.[Request Type],0))

Also check out the data type of your fields for it is uncommon to use the Cint to a text field format.

Sincerely,
Ed

LVL 12

Accepted Solution

by:Nathan Riley

Nathan Riley earned 2000 total points

ID: 350717452011-03-08

and then access if your using it.

strQuery = "SELECT Requests.*, RequestTypes.RequestTypeID, RequestType, [Approved/Unapproved].ID, [Approved/Unapproved].[Approved/Unapproved], " & _
                    "[Type of Leave].ID , TypeOfLeave " & _
                    "FROM Requests, RequestTypes, [Approved/Unapproved], [Type of Leave] " & _
                    "WHERE ((Requests.StartDate Between #" & strStartDate & "#" & " And #" & strEndDate & "#" & _
                    "OR Requests.EndDate Between #" & strStartDate & "#" & " And #" & strEndDate & "#)" & _
                    "AND Requests.Department = " & "'" & strDepartment & "'" & ")" & _
                    "AND nz(Requests.RequestTypeID,0) = RequestTypes.RequestTypeID " & _
                    "AND CInt(nz(Requests.[Approved/Unapproved],0)) = [Approved/Unapproved].ID " & _
                    "AND CInt(nz(Requests.[Request Type],0)) = [Type of Leave].ID " & _
                    "ORDER BY RequestID"

Open in new window

Author Comment

by:AronMcD

ID: 350718532011-03-08

I copied and pasted Gallitan's code and while I'm not getting the error anymore, I'm not getting the record that I should be getting. I'm going to keep testing....I'll get back to you.

LVL 15

Expert Comment

by:derekkromm

ID: 350718622011-03-08

..did you try mine?

LVL 15

Expert Comment

by:derekkromm

ID: 350721992011-03-08

i don't know why you completely ignored all my posts, considering i posted a correct solution twice...

Author Comment

by:AronMcD

ID: 350722002011-03-08

Gallitin's code worked. I was entering in the wrong values when testing..it's been a long day. Anyway thanks to all of you. I appreciate it.

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