Setting FilterExpression on GridView component at runtime in C#

Hello,
I have an application that queries an SQL table for a list of patients. The results of this query are displayed on a GridView component. I have the component coded to populate with patients information at runtime.  I am not sure how to programmatically set the filter expression for any of the columns.  (I can set FilterExpression within aspx but this is not an option for the application and I need to have FilterExpression set/configured at runtime.  Is this possible in C#?

Thank you!

Here is my method:

// I would like to filter the query results based on text entered in a component called Label1.Text to filter [clientLast]
 protected void BindGrid()
        {
            DataTable dt = new DataTable();
            SqlConnection connection = new SqlConnection(System.Configuration.ConfigurationManager.ConnectionStrings["PEIGenericConnectionString"].ConnectionString);
            string strSelect = @"SELECT [clientFirst] AS 'First Name', [clientMI] AS 'MI', [clientLast] AS 'Last Name', CONVERT(VARCHAR, [dob], 111) AS 'DOB' FROM [Individual_Client] WHERE [programNameID] = @programNameID";

            SqlCommand cmd = new SqlCommand(strSelect, connection);
            connection.Open();

            cmd.Parameters.Add("@programNameID", SqlDbType.Int, 2);
            cmd.Parameters["@programNameID"].Value = Convert.ToInt32(Request.QueryString["programNameID"]);

            SqlDataAdapter ad = new SqlDataAdapter(cmd);

            ad.Fill(dt);
            if (dt.Rows.Count > 0)
            {
                GridView1.DataSource = dt;
                GridView1.DataBind();
            }
            else
                return;  
        }

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