SELECT SRD_SUGG_ID SUG_ID ,SRD_SUBJECT SUG_SUBJECT, '~/Default2.aspx?id='||SRD_SUGG_ID NAVIGATE_URL
FROM T_SM_REG_DET WHERE SRD_FL_ACTIVE='Y' ORDER BY 1
<asp:HyperLinkField DataTextField="SRD_SUGG_ID" DataNavigateUrlFields="NAVIGATE_URL "
Target="_blank" HeaderText="Sugg. ID" />
Modifie your query like this. And use column navigate_url to hyperlink field.
Just try it.