ID Field in Custom SQL and Setting a Unique Default for New Rows

Montreux Yes, I use Dashboard Extenders for this.  Here's some example code to help you get started.  I almost never use the STE's internal save/update functionality.  Besides being fussy and undocumented, it doesn't (that I know of) stub out for data validation.

Private Function SaveRecords(si As SessionInfo, args As DashboardExtenderArgs) As Object
  Dim strSql As String = String.Empty
  Dim strDate As String = String.Empty
  Dim saveDataTaskResult As Object = Nothing
  Dim pKTheId As String = String.Empty
  Dim strValidationMsg = String.Empty

  Try
    'Not cancelling the default save even though nothing will be saved using the STE allows the UI to refresh with the new values
    saveDataTaskResult = New XFSqlTableEditorSaveDataTaskResult() With {
      .IsOK = True,
      .ShowMessageBox = False,
      .Message = "",
      .CancelDefaultSave = False
    }
    pKTheId = args.NameValuePairs.XFGetValue("pKTheId", "0")
    For Each row As XFEditedDataRow In args.SqlTableEditorSaveDataTaskInfo.EditedDataRows
      'Add any data validation here
      strValidationMsg = ValidateRecord(si, args, row)
      strDate = Date.Parse(row.ModifiedDataRow.Item("CustomDate")).ToString("yyyy-MM-dd")
      strSql = $"UPDATE XFW_CustomTable SET CustomAmount={row.ModifiedDataRow.Item("CustomAmount")}, Descr='{row.ModifiedDataRow.Item("Descr")}' WHERE CustomDate='{strDate}' and pKTheId={pKTheId}"
      Using DbConn As DbConnInfo = BRApi.Database.CreateApplicationDbConnInfo(si)
        BRApi.Database.ExecuteSql(DbConn, strSQL, True)
      End Using
    Next
    'We already added the new/updated records.  No need to use the SqlTableEditor to do it - so we clear them here.
        args.SqlTableEditorSaveDataTaskInfo.EditedDataRows.RemoveAll(Function(x) x.InsertUpdateOrDelete = DbInsUpdateDelType.Insert)
        args.SqlTableEditorSaveDataTaskInfo.EditedDataRows.RemoveAll(Function(x) x.InsertUpdateOrDelete = DbInsUpdateDelType.Update)

    Catch ex As Exception
         Throw New XFException($"{Environment.NewLine}{Me.GetType().ToString()}.{System.Reflection.MethodBase.GetCurrentMethod().Name}(): {ex.Message}:{Environment.NewLine}{strSql}", ex)
    End Try
  
  Return saveDataTaskResult
End Function

private function ValidateRecord(si As SessionInfo, args As DashboardExtenderArgs, row As XFEditedDataRow) As String
  Dim strValidationMsg as String = String.Empty
  'validation code here...
  
  return strValidationMsg
End Function


Private Function GetNextpKTheId(si As SessionInfo) As String
    Dim pKTheId As String = String.Empty
  Dim strSql as String = String.Empty

    Try
    strSql = "SELECT COALESCE(MAX(pKTheId), 0)+1 as NextpKTheId From XFW_CustomTable"
    Using DbConn As DbConnInfo = BRApi.Database.CreateApplicationDbConnInfo(si)
      pKTheId = BRApi.Database.ExecuteSql(DbConn, strSQL, True).Rows(0).Item("NextpKTheId")
    End Using
     Catch ex As Exception
        Throw New XFException($"{Environment.NewLine}{Me.[GetType]().ToString()}.{System.Reflection.MethodBase.GetCurrentMethod().Name}(): {ex.Message}:{Environment.NewLine}{strSql}", ex)
    End Try

    Return pKTheId
End Function