How to compare two DATE values based only on date part in Oracle?

Question

I am trying to get counts for last 30 days with the following query -

SELECT date_occured, COUNT(*) FROM problem
WHERE date_occured >= (CURRENT_DATE - 30)
GRO         


        

Answer 1

For this condition you only need to TRUNC the right-hand side:

WHERE date_occured >= TRUNC(CURRENT_DATE - 30)

Why? Because if TRUNC(date_occured) is later than TRUNC(CURRENT_DATE - 30), then any moment in time after TRUNC(date_occured) is bound to be later than TRUNC(CURRENT_DATE - 30) too.

It is obviously always true that date_occured >= TRUNC(date_occured) (think about it).

Logic says that if A >= B and B >= C then it follows that A >= C

Now substitute:

• A : date_occured
• B : TRUNC(date_occured)
• C : TRUNC(CURRENT_DATE - 30)