You can add a SqlDataSource. Configure it so that it fetches your desired list from DB. Then attach it to the CheckBoxList as shown below.
<asp:CheckBoxList runat="server" ID="mycheckboxlst" DataValueField="City"
DataSourceID="SqlDataSource1" DataTextField="FirstName"></asp:CheckBoxList>
<asp:SqlDataSource ID="SqlDataSource1" runat="server"
ConnectionString="<%$ ConnectionStrings:SampleDatabaseConnectionString %>"
SelectCommand="SELECT * FROM [CustomerInfo]"></asp:SqlDataSource>
Note that you need to set
DataValueField
and
DataTextField
properties to bind the text and value for each check box.