How to Compare a empName and Value? - sql

Question

Good morning,
Here is the situation: Have a column of credit card transactions that lists employee names and charge amounts a.k.a debits. In the same column it also lists employee names with an equal negative amount which shows a credit to the account.
What I am trying to do is to find the employee name and charge amount. Then cycle through the list and find the corresponding negative amount.
For example:
John Doe, $100
Jane Doe, $200
Sam Smith, $300
John Doe, -$100
When you run this module your results should return the names of Jane Doe and Sam Smith because only the records for John Doe had both a positive and negative value.
I have gotten very close to an answer but the solution falls apart when there are duplicate values.
For example:
John Doe, $100
John Doe, $100
John Doe, -$100
In this solution the result should be John Doe, $100
So far I have tried with Access, VBA, and SQL but have not come up with an answer.
For the solution, I don't really care if it means adding another object such as a table or a query to perform the comparison part. In the end I need to see a list of matched and unmatched employee names and values.
Additionally, I thought about adding on a column to my table that has a Boolean logic to show the two "matched" records as this will be a database and we don't necessarily want to delete the matched rows from the table master.
Thanks in advance!

Answer 1

You could add a Boolean field Cleared, and then run a simple loop in VBA to mark those set of record that match as cleared:
Public Function ClearTransactions()
Dim db As DAO.Database
Dim rs1 As DAO.Recordset
Dim rs2 As DAO.Recordset
Dim Criteria As String
Set db = CurrentDb
Set rs1 = db.OpenRecordset("Select * From Transaction Where Value > 0 And Cleared = False Order By Id")
Set rs2 = db.OpenRecordset("Select * From Transaction Where Value < 0 And Cleared = False Order By Id")
While Not rs1.EOF
Criteria = _
"Id > " & rs1!Id.Value & " And " & _
"EmpName = '" & rs1!EmpName.Value & "' And " & _
"Value = " & Str(-rs1!Value.Value) & " And " & _
"Cleared = False"
rs2.FindFirst Criteria
If rs2.NoMatch = False Then
rs1.Edit
rs1!Cleared.Value = True
rs1.Update
rs2.Edit
rs2!Cleared.Value = True
rs2.Update
End If
rs1.MoveNext
Wend
rs2.Close
rs1.Close
Set rs2 = Nothing
Set rs1 = Nothing
Set db = Nothing
End Function

Answer 2

I assume your table has a Primary Key (I'll call it TransactionID and assume it's Long Integer - adjust following code as necessary), in which case I would create a tblMatches with columns DebitID and CreditID to record pairs of entries that tie up. To populate this table:
Dim rsDebits As Recordset
Dim lngCreditID as Long
Set rsDebits = CurrentDb.OpenRecordset ("SELECT * FROM tblTransactions " & _
"WHERE ChargeAmount > 0 And TransactionID Not In " & _
"(SELECT DebitID From tblMatches)")
Do While Not rsDebits.EOF
lngCreditID = Nz(DMin("TransactionID", "tblTransactions", _
"EmpName = '" & rsDebits!EmpName & "' And " _
"ChargeAmount = " & -rsDebits!ChargeAmount & " And " _
"TransactionID Not In (SELECT CreditID From tblMatches)"), 0)
If lngCreditID > 0 Then
CurrentDb.Execute "INSERT INTO tblMatches (DebitID, CreditID) " & _
"VALUES (" & rsDebits!TransactionID & ", " & lngCreditID & ")"
End If
rsDebits.MoveNext
Loop
Set rsDebit = Nothing
You can now write a query joining this tblMatches to tblTransactions (twice, once joined ON tblTransactions.TransactionID = tblMatches.DebitID and the other one ON tblTransactions.TransactionID = tblMatches.CreditID) to show all the various entries that match up. To get a list of unmatched entries you'll need to design a query along the lines of
SELECT * FROM tblTransactions
WHERE TransactionID Not In (Select DebitID From tblMatches)
And TransactionID Not In (Select CreditID From tblMatches)