Do not set DataTypeCompatibility=80 in ADO connection string with old…

… SQLOLEDB driver. Probably solves some connection issues, see https://www.heidisql.com/forum.php?t=35208

source/dbconnection.pas

@@ -2140,11 +2140,15 @@ procedure TAdoDBConnection.SetActive(Value: Boolean);
       'User ID='+Parameters.Username+';'+
       'Network Library='+NetLib+';'+
       'Data Source='+DataSource+';'+
-      'Application Name='+AppName+';'+
+      'Application Name='+AppName+';'
+      ;
+    if Parameters.LibraryOrProvider = 'MSOLEDBSQL' then begin
       // Issue #423: MSOLEDBSQL compatibility with new column types
       // See https://docs.microsoft.com/en-us/sql/connect/oledb/applications/using-ado-with-oledb-driver-for-sql-server?view=sql-server-2017
-      'DataTypeCompatibility=80;'
-      ;
+      // Do not use with old driver, see https://www.heidisql.com/forum.php?t=35208
+      FAdoHandle.ConnectionString := FAdoHandle.ConnectionString +
+        'DataTypeCompatibility=80;';
+    end;
 
     // Pass Database setting to connection string. Required on MS Azure?
     if (not Parameters.AllDatabasesStr.IsEmpty) and (Pos(';', Parameters.AllDatabasesStr)=0) then