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

Two things to remeber:

1. ORDER is a keyword, so please use another table name
2. CASE statement should be ended with END not with END AS

Possible solution:

SELECT O.OrderId,
  O.OrderDate,
  CASE
    WHEN H.HolidayDate IS NOT NULL
    THEN 'Public holiday'
    ELSE TO_CHAR(O.OrderDate, 'Day')
  END DAY
FROM ORDER_TABLE O
LEFT JOIN HOLIDAY_TABLE H
ON H.HolidayDate=O.OrderDate;