Hi,
This is the simple way to update single row of record with button in gridview..

GridViewRow gvr;
string gvDataKey;

gvr = GridView1.Rows(e.CommandArgument)
gvDataKey = gvr.Cells(1).Text


sqlStr = "UPDATE tblUser SET uActive = 1 WHERE uPrimaryId = " + gvDataKey + ""

Thanks..

S.Balasubramanian..