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MS Access DAO Recordset sorting bug in VB6?

Posted on 2009-06-30
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Last Modified: 2012-05-07
Hello,

I am using Access 2002 and VB6.

I'm attempting to compare 2 similar tables in the same db file, and show the changes.

Each table has over 224,000 rows, and if they are slightly different or absolutely identical, I get the same problem.....

I load each table into recordsets (rs1 and rs2) via DAO and an SQL query and then cycle through each entry (rs.MoveNext) and compare the field values (rs.Fields(i))

Here is an example of the issue:

The following entries are identical in both tables

Name      Last Known Address      Amount      Description      Year      Organisation
PYNENBURG CONSTRUCTIONS      331 Pearsons Lane Robertson      $62.50      DEPOSIT      1993      WOLNG CITY CNCL
PYNENBURG CONSTRUCTIONS      331 Pearsons Lane Robertson      $140.00      DEPOSIT      1992      WOLNG CITY CNCL
PYNENBURG CONSTRUCTIONS      331 Pearsons Lane Robertson      $140.00      DEPOSIT      1992      WOLNG CITY CNCL
PYNENBURG CONSTRUCTIONS      331 Pearsons Lane Robertson      $143.50      DEPOSIT      1993      WOLNG CITY CNCL
PYNENBURG CONSTRUCTIONS      331 Pearsons Lane Robertson      $143.50      DEPOSIT      1993      WOLNG CITY CNCL
PYNENBURG CONSTRUCTIONS      331 pearsons Lane Robertson      $143.50      DEPOSIT      1993      WOLNG CITY CNCL
PYNENBURG CONSTRUCTIONS      331 Pearsons Lane Robertson      $143.50      DEPOSIT      1993      WOLNG CITY CNCL
PYNENBURG CONSTRUCTIONS      331 Pearsons Lane Robertson      $145.00      DEPOSIT      1994      WOLNG CITY CNCL
PYNENBURG CONSTRUCTIONS      331 Pearsons Lane Robertson      $335.00      DEPOSIT      1997      WOLNG CITY CNCL

If you look carefully there are 2 entries with $143.50, but one of the address street-name; "Pearsons" starts with a lower case "p" and one is an upper case "P"

rs2 puts them in the correct ascii sort order, "P" before "p"

but rs1 puts "p" before "P"

is it a sort priority issue or a bug?

help! :)

thanks,
Chris

Set db = DBEngine.OpenDatabase(OSR_DB)
 
    query = "select * from " & CURRENT_TABLE & " order by Name, [Last Known Address], Amount, Description, Year, Organisation"
    Set rs1 = db.OpenRecordset(query)
 
    query = "select * from " & TEMP_TABLE & " order by Name, [Last Known Address], Amount, Description, Year, Organisation"
    Set rs2 = db.OpenRecordset(query)

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Question by:schmuck2
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Accepted Solution

by:
peter57r earned 500 total points
ID: 24752060
Jet is not case sensitive.
The different resuts are just occurring by chance.

If you want to force a case sensitive order you would have to use a convert to hex function on your address field and sort on the result of the function.
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Author Comment

by:schmuck2
ID: 24752196
thanks Peter,
can you supply the code? :)
cheers
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LVL 77

Expert Comment

by:peter57r
ID: 24752229
Function StrToHex(S As Variant) As Variant
'
' Converts a string to a series of hexadecimal digits.
' For example, StrToHex(Chr(9) & "A~") returns 09417E.
'
   Dim Temp As String, I As Integer
      If VarType(S) <> 8 Then
         StrToHex = S
      Else
         Temp = ""
      For I = 1 To Len(S)
         Temp = Temp & Format(Hex(Asc(Mid(S, I, 1))), "00")
      Next I
         StrToHex = Temp
      End If
End Function
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Author Comment

by:schmuck2
ID: 24753225
thanks for that
I had an even better idea
when I do the compare between the fields of rs1 and rs2, I now UCase() both values
it works a treat
thanks for your initial comment
will award full points
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LVL 5

Expert Comment

by:BrianVSoft
ID: 24753264
It seems one of these tables is a replica of the other and that they are an Indexed recordset (Ie. there would be a Primary Key)
If there is a primary key, you should be using that to compare the records!
You should never use movenext on two record sets to compare them - that will fail if a record has been deleted.
1. You could add that primary key to an "ORDER BY" clause to ensure both records are in the same order and then as you movenext thru both sets you can check to see if the fields used by that key are the same (that will cover a deleted record) If you need to check the upper/lower case of Names etc. use the Option Compare Binary mode.
2. You could open the tables directly via DAO, Set the Tables.Index = to the Primary key, MoveNext thru one table, Table2.Seek "=", Key2, Key2 each record in the other table and see if you get a Table2.NoMatch
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LVL 77

Expert Comment

by:peter57r
ID: 24753326
Yes that is simpler.
But from the way you expressed the Q i assumed that you wanted to identify the difference in case as a genuine difference.

If you don't care about case then you can just test
if t1.field1 = t2.field1 then ...... as Access will ignore case.

(unless you have set Option Compare Binary at the top of your module)
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Author Comment

by:schmuck2
ID: 24759185
Hi Brian,
thanks for the advice
My code is now working perfect (attached)
thanks for your help guys
Sub CompareTables()
 
Dim db As DAO.Database
Dim rs1 As DAO.Recordset
Dim rs2 As DAO.Recordset
Dim i As Integer
Dim query As String
Dim rs1Size As Long
Dim rs1Pos As Long
Dim value1 As String
Dim value2 As String
Dim compare_value As Integer
 
    lblStatus = "Loading and Sorting Table RecordSets...."
    Me.Refresh
    
    Set db = DBEngine.OpenDatabase(OSR_DB)
 
    query = "select * from [" & CURRENT_TABLE & "] order by Name, [Last Known Address], Amount, Description, Year, Organisation"
    Set rs1 = db.OpenRecordset(query)
 
    query = "select * from [" & TEMP_TABLE & "] order by Name, [Last Known Address], Amount, Description, Year, Organisation"
    Set rs2 = db.OpenRecordset(query)
 
    rs1Size = rs1.RecordCount
    rs1Pos = 1
    
    lblStatus = "Comparing Records and Updating Table...."
    Me.Refresh
    
    Do Until rs2.EOF
                    
        If rs1Pos > rs1Size Then 'new records at end of temp table
            rs1.AddNew
            For i = 0 To 5
                If LenB(rs2(i)) <> 0 Then rs1(i) = rs2(i)
            Next i
            'add "Date Added"
            rs1(6) = Format(Now, "d/mm/yyyy")
            rs1.Update
            rs2.MoveNext
        Else
            'compare values
            compare_value = 0
            For i = 0 To 5
                'access ignore hyphens when sorting, so remove them for comparison test
                'access also ignores case, so UCase everything
                value1 = UCase(Replace("" & rs1.Fields(i), "-", ""))
                value2 = UCase(Replace("" & rs2.Fields(i), "-", ""))
                If value1 > value2 Then 'new record
                    compare_value = 1
                    Exit For
                ElseIf value1 < value2 Then 'removed record
                    compare_value = -1
                    Exit For
                End If
            Next
                
            If compare_value = 0 Then 'matching record
                rs1Pos = rs1Pos + 1
                rs1.MoveNext
                rs2.MoveNext
            ElseIf compare_value = 1 Then 'new record
                rs1.AddNew
                For i = 0 To 5
                    If LenB(rs2(i)) <> 0 Then rs1(i) = rs2(i)
                Next i
                'add "Date Added"
                rs1(6) = Format(Now, "d/mm/yyyy")
                rs1.Update
                rs2.MoveNext
            ElseIf compare_value = -1 Then 'removed record
                'add "Date Removed" (only if already blank)
                If IsNull(rs1(7)) Then
                    rs1.Edit
                    rs1(7) = Format(Now, "d/mm/yyyy")
                    rs1.Update
                End If
                rs1Pos = rs1Pos + 1
                rs1.MoveNext
            End If
        End If
    Loop
 
     'records removed from end of table?
     If rs2.EOF And rs1Pos < rs1Size Then
        Do Until rs1Pos > rs1Size
            'add "Date Removed" (only if already blank)
            rs1.Edit
            If IsNull(rs1(7)) Then
                rs1(7) = Format(Now, "d/mm/yyyy")
            End If
            rs1.Update
            rs1.MoveNext
            rs1Pos = rs1Pos + 1
        Loop
    End If
    
    rs1.Close
    rs2.Close
    
End Sub

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