Populate DropDown List from Database in ASP.NET & C#

It is often useful to allow users to select items from a dropdown list for input into a web form. However, this can be somewhat too limiting in certain situations.
This tutorial will show how we can dynamically populate a dropdown menu with records from a database.
First, we start by declaring the assembly reference:

using System.Data.SqlClient;

In our Web.config, we declare the connection string:

<appSettings> <add key="ConnString" value="Data Source=CLIENT-TASK2\SQLEXPRESS;Initial Catalog=BasicDataAccess;Integrated Security=True"/> </appSettings>

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The ASPX page will look something like this:

<form id="form1" runat="server"> <div align="center"> <table><tr><th>Name:</th><td><asp:DropDownList ID="DropDownList1" runat="server"> </asp:DropDownList></td></tr> <tr><th>City:</th><td><asp:DropDownList ID="DropDownList2" runat="server"> </asp:DropDownList></td></tr></table> </div> </form>

In the code-behind, we can create two methods and then call them on page load:

using System; using System.Data; using System.Configuration; using System.Web; using System.Web.Security; using System.Web.UI; using System.Web.UI.WebControls; using System.Web.UI.WebControls.WebParts; using System.Web.UI.HtmlControls; using System.Data.SqlClient; public partial class _Default : System.Web.UI.Page { protected void Page_Load(object sender, EventArgs e) { Populate1(); Populate2(); } public void Populate1() { SqlCommand cmd = new SqlCommand("SELECT * FROM [tblOne]", new SqlConnection(ConfigurationManager.AppSettings["ConnString"])); cmd.Connection.Open(); SqlDataReader ddlValues; ddlValues = cmd.ExecuteReader(); DropDownList1.DataSource = ddlValues; DropDownList1.DataValueField = "theName"; DropDownList1.DataTextField = "theName"; DropDownList1.DataBind(); cmd.Connection.Close(); cmd.Connection.Dispose(); } public void Populate2() { SqlCommand cmd = new SqlCommand("SELECT * FROM [tblOne]", new SqlConnection(ConfigurationManager.AppSettings["ConnString"])); cmd.Connection.Open(); SqlDataReader ddlValues; ddlValues = cmd.ExecuteReader(); DropDownList2.DataSource = ddlValues; DropDownList2.DataValueField = "theCity"; DropDownList2.DataTextField = "theCity"; DropDownList2.DataBind(); cmd.Connection.Close(); cmd.Connection.Dispose(); } }