C# WinApp database กับ extension method ก็ สะดวกสบายดีไปอีกแบบ

 public static class extDatabase
    {
        public static System.Data.SqlClient.SqlConnection ToSqlConnection(this string input)
        {
            System.Data.SqlClient.SqlConnection cnn;
            try
            {
                cnn = new System.Data.SqlClient.SqlConnection(input);
                cnn.Open();
            }
            catch { cnn = null; }
            return cnn;
        }

        public static System.Data.OleDb.OleDbConnection ToOleDbConnection(this string input)
        {
            System.Data.OleDb.OleDbConnection cnn;
            try
            {
                cnn =  new System.Data.OleDb.OleDbConnection(input);
                cnn.Open();
            }
            catch { cnn = null; }
            return cnn;
        }

        public static System.Data.Odbc.OdbcConnection ToOdbcConnection(this string input)
        {
            System.Data.Odbc.OdbcConnection cnn;
            try
            {
                cnn = new  System.Data.Odbc.OdbcConnection(input);
                cnn.Open();
            }
            catch { cnn = null; }
            return cnn;
        }

        public static System.Data.DataTable ToDataTable(this string SQL,System.Data.SqlClient.SqlConnection cnn)
        {
            System.Data.DataSet ds = new System.Data.DataSet();
            System.Data.DataTable dt;
            try
            {
                System.Data.SqlClient.SqlDataAdapter adapter = new System.Data.SqlClient.SqlDataAdapter(SQL, cnn);
                adapter.Fill(ds);
                dt= ds.Tables[0];
            }
            catch { dt = null; }
            return dt;
        }

        public static System.Data.DataTable ToDataTable(this string SQL, System.Data.OleDb.OleDbConnection cnn)
        {
            System.Data.DataSet ds = new System.Data.DataSet();
            System.Data.DataTable dt;
            try
            {
                System.Data.OleDb.OleDbDataAdapter adapter = new System.Data.OleDb.OleDbDataAdapter(SQL, cnn);
                adapter.Fill(ds);
                dt = ds.Tables[0];
            }
            catch { dt = null; }
            return dt;
        }
        public static System.Data.DataTable ToDataTable(this string SQL, System.Data.Odbc.OdbcConnection cnn)
        {
            System.Data.DataSet ds = new System.Data.DataSet();
            System.Data.DataTable dt;
            try
            {
                System.Data.Odbc.OdbcDataAdapter adapter = new System.Data.Odbc.OdbcDataAdapter(SQL, cnn);
                adapter.Fill(ds);
                dt = ds.Tables[0];
            }
            catch { dt = null; }
            return dt;
        }

    }

dataGridView1.DataSource = "SELECT *FROM  Instrument_Pipet".ToDataTable(DATA_CSharp.Properties.Settings.Default.DATA_ALS_ContactConnectionString.ToSqlConnection());