Need help optimizing vba display function - excel

Question

I have been doing some database work with excel both as the database and the database driver via macros with vba. I built a function that should parse through a list of database records with testID fields. I wanted to display each test only once based on it's testID, but the way the database is set up means I have to eliminate duplicate testID's. I do this by iterating through the recordset and checking the current test against the previous one before showing in the list. The problem I'm having is that the function is excruciatingly slow. For only 12 tests in the database, it takes about 3 seconds to display them in the view spreadsheet. I'd love to hear some ideas on how to optimize the run-time. Here's the function:
Public Function showAllTests()
Dim conn As ADODB.Connection
Dim rs As ADODB.Recordset
Dim cstring, sql As String
Dim r, c As Integer
Dim testsAr As Variant
Dim inAr As Boolean
cstring = "Provider = Microsoft.ACE.OLEDB.12.0; Data Source=I:\DBtrials.xlsx; Extended Properties=""Excel 12.0 Xml; HDR=YES;ReadOnly=False"";"
sql = "SELECT [TestID], [Status], [PFIBox], [WireType], [StartingDia], [Customer], [numSamples], [Assigned] FROM [Tests$]"
Set conn = New ADODB.Connection
Set rs = New ADODB.Recordset
Call conn.Open(cstring)
Set rs = conn.Execute(sql)
If rs.EOF Then
Range("C6:J1000").ClearContents
End If
r = 6
count = 0
'Iterates through the recordset, eliminating duplicates and populating cells in the tests sheet
While Not rs.BOF And Not rs.EOF
Dim prevID, currID As String
Dim currCell As Range
inAr = False
If Not count = 0 Then
prevID = ActiveWorkbook.Sheets("Tests").Cells(r - 1, 3).Value
currID = CStr(rs(0))
If prevID = currID Then
inAr = True
End If
End If
For c = 3 To (rs.Fields.count + 2)
Set currCell = ActiveWorkbook.Sheets("Tests").Cells(r, c)
If Not IsNull(rs(c - 3).Value) And inAr = False Then
currCell.Value = CStr(rs(c - 3))
ElseIf IsNull(rs(c - 3).Value) Then currCell.Value = ""
Else:
Exit For
End If
Next c
If inAr = False Then
r = r + 1
End If
rs.MoveNext
count = count + 1
Wend
conn.Close
Set conn = Nothing
End Function

Answer 1

use GROUP BY
sql = "SELECT [TestID], [Status], [PFIBox], [WireType], [StartingDia], [Customer], [numSamples], [Assigned] FROM [Tests$] GROUP BY [TestID]"
Also some of these drivers - Microsoft.ACE.OLEDB.12.0 etc have terrible perfomance in VBA. sometimes i get better perforamance from OBDC 6.2 than ADO