C# easier ways to filter values in data-grid by month

Question

Goal:

My goal is to filter datagrid by selected month from dropdown options.

January, February, March etc...

I'd like to know if there are easier methods to my current method..

Code:

public Schedule()
{
    InitializeComponent();
    RefreshGrid();

    Dictionary<string, string> allOptions = new Dictionary<string, string>();
    allOptions.Add("1", "All");
    allOptions.Add("2", "January");
    allOptions.Add("3", "February");
    allOptions.Add("4", "March");
    allOptions.Add("5", "April");
    allOptions.Add("6", "May");
    allOptions.Add("7", "June");
    allOptions.Add("8", "July");
    allOptions.Add("9", "August");
    allOptions.Add("10", "September");
    allOptions.Add("11", "October");
    allOptions.Add("12", "November");
    allOptions.Add("13", "December");

    Months.DataSource = new BindingSource(allOptions, null);
    Months.DisplayMember = "Value";
    Months.ValueMember = "Key";

}

public void RefreshGrid()
{
    string value = "";

    // Select All
    if(Months.SelectedIndex == 0)
    {
        value = "";
    }
    // Select * from January
    if(Months.SelectedIndex == 1)
    {
        value = " where month(date_purchased) = 1;";
    }
    // Select * from February
    if (Months.SelectedIndex == 2)
    {
        value = " where month(date_purchased) = 2;";
    }
    //... and son on...

    // MySQL connection string
    using (var conn = new MySqlConnection(ConnectionString.ConnString))
    {
        //Select query
        using (var mySqlDataAdapter = new MySqlDataAdapter("select * from table "+ value +";", conn))
        {
            using (var dataSet = new DataSet())
            {
                DataSet DS = new DataSet();
                mySqlDataAdapter.Fill(DS);

                //Assign headers to Data Grid View
                scheduleData.DataSource = DS.Tables[0];
                scheduleData.Columns[0].HeaderText = "ID";
                scheduleData.Columns[1].HeaderText = "Equipment Name";
                scheduleData.Columns[2].HeaderText = "Date Purchased";


                //Set visibility to false for the columns to work in the background
                scheduleData.Columns[0].Visible = false;
            }
        }
    }
}

private void Months_SelectedIndexChanged(object sender, EventArgs e)
{
    RefreshGrid();
}

This idea does work - but Seems like there is too much unnecessarily code. But I cannot think of an alternative.

Answer 1

Why not something simple like this:

var filter = Months.SelectedIndex == 0 ? null : 
    $" where month(date_purchased) = {Months.SelectedIndex};"

Also that dictionary initialization code is a lot of copy & paste, you could easily write it like this:

var allOptions = new Dictionary<string, string>()
{
    ["0"] = "All"
};

int idx = 1;
foreach(var month in DateTimeFormatInfo.CurrentInfo.MonthNames)
    allOptions.Add((idx++).ToString(), month);

Edit: also don't use data sets if you're only returning one data table, use the table versions of the database API instead.