มันขึ้นว่า Must declare the scalar variable "@name".

string strConn = WebConfigurationManager.ConnectionStrings["testConnectionString2"].ConnectionString;
            SqlConnection Conn = new SqlConnection(strConn);
            Conn.Open();
            string nam = search.Text;
            string sqlproduct = "SELECT* FROM empoy WHERE @name";
            SqlCommand com = new SqlCommand(sqlproduct, Conn);
            com.Parameters.Add("@name", SqlDbType.NVarChar).Value = nam;
            SqlDataAdapter da = new SqlDataAdapter(sqlproduct, Conn);
            DataSet ds = new DataSet();
            da.Fill(ds,"Pro");
            GridView1.DataSource = ds.Tables["Pro"];
            GridView1.DataBind();