SELECT * FROM 'Table_name' WHERE mobnum NOT IN
   (SELECT mobnum FROM 'Table_name' GROUP BY mobnum HAVING COUNT(*) >1 )
   AND add_date Like 'date' AND location = 'xyz'
  ORDER BY add_date ASC

id,name,attnum,mobnum,visitfrom,location,referenceblock,add_by,add_date,flag,sms_date_time