C＃Winforms-数据绑定或列表<T>

Question

I have here a method inside a class called PurchaseOrder. Here, I used List<string> to retrieve a list of suppliers and populate these lists in a combo box. The code actually works, but as I add more and more suppliers in my SQL Server database, I have been experiencing a little slowdown on the forms being loaded. How could I optimize such speed?

Below are two sets of codes, the method PopulateSuppliers() from PurchaseOrderClass.cs and a Form_Load event.

    public object PopulateSuppliers()
    {
        //Create an instance of a List of Strings.
        List<string> ListOfSuppliers = new List<string>();

        string sqlString = "SELECT CompanyName FROM tbl_suppliers WHERE Archived = 'False';";

        SqlConnection sqlConnection = new SqlConnection(connectionString);
        SqlCommand sqlCommand = new SqlCommand(sqlString, sqlConnection);

        sqlConnection.Open();
        sqlReader = sqlCommand.ExecuteReader();

        while (sqlReader.Read())
        {
            ListOfSuppliers.Add(sqlReader["CompanyName"].ToString());
        }

        sqlReader.Close();
        sqlConnection.Close();

        return ListOfSuppliers;
    }

    private void frmPurchaseOrderEditor_Load(object sender, EventArgs e)
    {
        ...

        //Populate a list of suppliers.
        cboSuppliers.DataSource = PurchaseOrder.PopulateSuppliers();

        ...
    }

Answer 1

Maybe creating an index on the Archived column might help.. But your code looks fine. However, if the list of suppliers is going to keep growing, think about the chances of replace your combo with a paged datagrid.

Also, always use a finally block when working with DDBB and dispose Commands and Connection classes there to release unmanaged resources.

Answer 2

Your code is perfectly fine i think...but if the data in the table is too much, then i don't think that combo box is the best option for you..try other alternatives...like GridView, ListView, Repeater...and there is always the client side.

When using any resource such as SqlReader, File, etc (All the classes library types which uses IDisposable interface) you should use "using" statement which will take care of allocating as well disposing of the resource...

click here for more info on using statement