private void CreateDataSources() { _dataSources.Clear(); if (checkBoxSqlServer.Checked) { var sqlSource = new SqlSource(textBoxSqlServer.Text); if (!sqlSource.TestConnection()) { MessageBox.Show("Could not connect to database. Please check the connection string.", "Error"); } else { _dataSources.Add(sqlSource); } } if (checkBoxCsvFile.Checked) { var csvSource = new CsvSource(textBoxCsvFile.Text); if (!csvSource.TestConnection()) { MessageBox.Show("Could not find the CSV file. Please check the path to the file.", "Error"); } else { _dataSources.Add(csvSource); } } if (checkBoxXmlFile.Checked) { var xmlSource = new XmlSource(textBoxXmlFile.Text); if (!xmlSource.TestConnection()) { MessageBox.Show("Could not find the XML file. Please check the path to the file.", "Error"); } else { _dataSources.Add(xmlSource); } } }