conditional select statement in oracle

Question

I have two tables called order and public holiday as following:

Order Table:

OrderId      OrderDate
---------------------------
    1        10 Mar 2017
         


        

Answer 1

You can use an outer join like this:

SELECT OrderId,
       OrderDate, 
       case when holidaydate is not null then  'Public holiday' 
             else to_char(OrderDate, 'Day') end as DAY
from orders
     left outer join holidays
        on OrderDate = holiday_date ;

If the dates match holidaydate is not null so the CASE clause displays your desired string otherwise it displays the day of the orderdate .

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order is a reserved word. Presumably your real table has a different name, to avoid the ora-00903 error. I have used orders in my example, so you will need to edit my code to match your table name(s).