GridView show command field only if user owns the record!

in the onRowDataBoundEvent of the gridview you can retrieve the DataRowView. If the userid is in the data (even if that field is not shown in your gridview!) you can then check if the userid is the same as the logged in user.
Than do a findControl on the gridviewrow and set the control to visible = true or false.

in my example a tooltip is added to an image based on a value in the DataRowView.

protected void grdAppSettingsORDB(Object sender, GridViewRowEventArgs e)
    {
        if (e.Row.RowType.Equals(DataControlRowType.DataRow))
        {
            DataRowView dataRow = (DataRowView)e.Row.DataItem;
            Image imgHelp = (Image)e.Row.FindControl("imgHelp");
            if (null != imgHelp)
            {
                imgHelp.ToolTip = dataRow["Description"].ToString();
            }
        }
    }