Dim strSQL
Dim rstTemp as New ADODB.Recordset
strSQL="SELECT COUNT(*) AS Amount FROM TblTemp WHERE FldName='ABC'"
rstTemp.Open strSQL, cnnMain, adOpenKeyset, adLockReadOnly
If rstTemp.Fields("Amount").Value= 0  Then
      MsgBox "Not exist!"
Else
      MsgBox "Exist!"
End If

Dim strSQL
Dim rstTemp as New ADODB.Recordset
strSQL="SELECT TOP 1 * FROM TblTemp WHERE FldName='ABC'"
rstTemp.Open strSQL, cnnMain, adForwardOnly, adLockReadOnly
If rstTemp.EOF Then
      MsgBox "Not exist!"
Else
      MsgBox "Exist"
End If

rstData.Open "SELECT TOP 1 * FROM TblTemp WHERE FldName='ABC'", cnnMain, adOpenStatic, adLockOptimistic

select 'exists' where exists (select * from FROM TblTemp WHERE FldName='ABC')

select 'exists' where exists (select top  1  * from FROM TblTemp WHERE FldName='ABC')