private void UpdateTextBoxSelectSql() { if (textBoxSelectSql == null) { return; } if (JoinTables.Count == 0) { textBoxSelectSql.Text = string.Empty; return; } string alias = JoinTables[0].Alias; string where = Target.GetKeyConditionSQL(alias, string.Empty, 0); textBoxSelectSql.Text = JoinTables.GetSelectSQL(where, string.Empty, null); }