Question

I have a simple query to filter out the due_date value is today.

SELECT *
  FROM ORDER
  WHERE DUE_DATE = CURRENT_DATE AND
        ROWNUM <= 10
  ORDER BY DUE_DATE ASC

However, even I have a bunch of order has due date as today, the query actually return 0 rows.

How come? Thanks in advance.

Sorry I forget to mention the DUE_DATE is of type Date

Answer 1

You need to either truncate your dates, as in

SELECT *
  FROM ORDER
  WHERE TRUNC(DUE_DATE) = TRUNC(CURRENT_DATE) AND
        ROWNUM <= 10
  ORDER BY DUE_DATE ASC 

or use a ranged comparison, as in

SELECT *
  FROM ORDER
  WHERE DUE_DATE BETWEEN TRUNC(CURRENT_DATE)
                     AND TRUNC(CURRENT_DATE) + INTERVAL '1' DAY - INTERVAL '1' SECOND AND
        ROWNUM <= 10
  ORDER BY DUE_DATE ASC 

The latter example may perform better because an index can be used (assuming you have an index on DUE_DATE). Of course, you could also add a function-based index on TRUNC(DUE_DATE) in which case either would likely perform equally well.

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