Question : increase database access performance - ms-access

I have a code [attached] which takes two tables at a time from an access databases, compare values for each row and column and if it finds any differences it reports to the user.

Unfortunately it becomes slower and slower as the database grow.

I really want it fast and i don't know what to do. should i use Threading. I have attached the code

Anthony

Public Function showDifferences(ByVal ds As String, ByVal co As System.Data.OleDb.OleDbConnection) As Boolean
Dim z As Integer
Dim v, p, vname As String

z = 0

showDifferences = False
'there are several tables and pick one at a time- they are in the table tblRecords
'e.g. compare values in table [master] against those in table [vmaster]

For t As Long = 0 To tblRecords.Rows.Count - 1
Application.DoEvents()
'exclude these tables
If sectionsToEculude(tblRecords.Columns("recname").ColumnName) = True Then Continue For
If Trim(mainver).Length = 0 Then
tstr = "SELECT * FROM [" & tblRecords.Rows(t)("recname") & "] " & ds
Else
tstr = "SELECT * FROM [" & mainver & tblRecords.Rows(t)("recname") & "] " & ds
End If

cm = New OleDb.OleDbCommand
cm.CommandText = tstr
cm.Connection = co
dr = cm.ExecuteReader
If dr.HasRows Then
While dr.Read
criteria = ""
'construct the sql criteria for each table
criteria = Trim(Mid(ds, 1, ds.Length - 1)) & " and "
For i As Int16 = 1 To tblRecords.Rows(t)("nid")
If Not IsDBNull(dr(tblRecords.Rows(t)("id" & (i - 1).ToString))) Then
If Not IsNumeric(dr(tblRecords.Rows(t)("id" & (i - 1).ToString))) Then
criteria = criteria & tblRecords.Rows(t)("id" & i - 1) & "='" & dr(tblRecords.Rows(t)("id" & (i - 1).ToString)) & "' and "
Else
criteria = criteria & tblRecords.Rows(t)("id" & i - 1) & "=" & dr(tblRecords.Rows(t)("id" & (i - 1).ToString)) & " and "
End If
Else
criteria = criteria & tblRecords.Rows(t)("id" & i - 1) & " Is null and "
End If
Next
criteria = Mid(criteria, 1, criteria.Length - 5)

If Trim(mainver).Length = 0 Then
tstr = "SELECT * FROM [v" & tblRecords.Rows(t)("recname") & "] " & criteria & ";"
Else
tstr = "SELECT * FROM [" & tblRecords.Rows(t)("recname") & "] " & criteria & ";"
End If

'now i have the entire SQL statement and the criteria appended to it.

cmd = New OleDb.OleDbCommand
cmd.CommandText = tstr
cmd.Connection = co

ddr = cmd.ExecuteReader
If tblRecords.Rows(t)("recname") = "master" Then recordExists = False 'not in verification
'reader [dr] is holding values for table [master]
'reader [ddr] is holding values for table [vmaster] for example

If ddr.HasRows Then
recordExists = True
'check duplicates
dup1.Clear()
dup2.Clear()
While ddr.Read
'compare field value by field value
'if any is different [showDifferences] is true
'report
For f As Int16 = idNames.Count To dr.FieldCount - 1
vname = dr.GetName(f)
If IsDBNull(dr(f)) Then : v = Nothing : Else : v = Trim(dr(f)) : End If
If IsDBNull(ddr(vname)) Then : p = Nothing : Else : p = Trim(ddr(vname)) : End If
If Not variablesToExclude(vname) Then
If v <> p Then
showDifferences = True
ddr.Close()
ddr = Nothing
cmd.Dispose()
Exit Function
End If
End If
Next
End While

Else
'tell user if the record is not found in [vmaster]
If tblRecords.Rows(t)("recname") = "master" Then recordExists = False
End If
ddr.Close()
ddr = Nothing
cmd.Dispose()
Application.DoEvents()
End While

End If
dr.Close()
dr = Nothing
cm.Dispose()
Next
cmd.Dispose()
End Function

Answer : increase database access performance - ms-access

Aaaaahh ... ok the problem is that you don't have to provide the data element ... all you do is to procide the name of the function.

                       
         
           
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