cust_email   visit_timestamp  category_visit  transaction_timestamp  category_trans
abc@email.com 2015:12:10 12:00:00 Mobiles
abc@email.com 2015:12:10 12:03:22 Mobiles     2015:12:10 12:03:54     Mobiles
abc@email.com 2015:12:10 12:05:22 Fashion     2015:12:10 12:05:54     Fashion

category_trans  NO_OF_VISITS_BEFORE  Category_of_visits_BEFORE  NO_of_VISITS_AFTER  Category_of_visits_AFTER
Mobiles         2                    Mobiles                    1                  Fashion
Fashion         2                    Mobiles                    null               null
Fashion         1                    Fashion                    null               null