date.SetToGMTime();\r
date.Add(0,0,0,-20);\r
st=m_db->Prepare("DELETE FROM tblIdentity WHERE IdentityID IN (SELECT tblIdentity.IdentityID FROM tblIdentity LEFT JOIN tblMessage ON tblIdentity.IdentityID=tblMessage.IdentityID WHERE tblMessage.IdentityID IS NULL AND tblIdentity.DateAdded<?);");\r