A Multiple Selection DropDownList (a CheckBoxList )

Question

I need a code in C#

like i am having an gridview and above the gridview i am having a drop down for different column in the dropDown i can select all the values or multiple values so can u please advice me on this how can i achieve this .

or in Short i want for gridview

<pre>A Multiple Selection DropDownList (a CheckBoxList Inside a DropDownList)</pre>

 

Based on the checkbox selection gridview data is populated .