php - If there is no value in the table, then query should return 0 -

this query

select (max(booking_id),0) bookingid booking; 

if there no value in table, query should return 0. how this??

two alternatives:

1. using ifnull:

   select ifnull(max(booking_id),0)) bookingid booking; 

2. using coalesce:

   select coalesce(max(booking_id),0)) bookingid booking; 

explanation:

ifnull can used in mysql. coalesce can used in rdbmss. coalesce returns first parameter in list not null.