问题
I can get the 15/02 - 21/06 date range data on every year from the query below.
SELECT * FROM dim_date
WHERE EXTRACT (MONTH FROM date_cal) BETWEEN 3 AND 5
OR (EXTRACT (MONTH FROM date_cal) = 2 AND EXTRACT (DAY FROM date_cal) >= 15)
OR (EXTRACT (MONTH FROM date_cal) = 6 AND EXTRACT (DAY FROM date_cal) <= 21)
But the problem is, when i want to find from year 2010 - 2012, I get back the same result.
Range that i want to get:
2010-02-15 - 2010-06-15
2011-02-15 - 2011-06-15
2012-02-15 - 2012-06-15
SELECT * FROM dim_date
WHERE EXTRACT (MONTH FROM date_cal) BETWEEN 3 AND 5
OR (EXTRACT (MONTH FROM date_cal) = 2 AND EXTRACT (DAY FROM date_cal) >= 15)
OR (EXTRACT (MONTH FROM date_cal) = 6 AND EXTRACT (DAY FROM date_cal) <= 21)
AND EXTRACT (YEAR FROM date_cal) BETWEEN 2010 AND 2012
Who can help me about this!
回答1:
Your problem is a lack of brackets: In SQL AND takes precedence over OR, so you need to put brackets around your whole previous expression:
SELECT * FROM dim_date
WHERE ( -- added bracket
EXTRACT (MONTH FROM date_cal) BETWEEN 3 AND 5
OR (EXTRACT (MONTH FROM date_cal) = 2 AND EXTRACT (DAY FROM date_cal) >= 15)
OR (EXTRACT (MONTH FROM date_cal) = 6 AND EXTRACT (DAY FROM date_cal) <= 21)
) -- added bracket
AND EXTRACT (YEAR FROM date_cal) BETWEEN 2010 AND 2012
Without the brackets, you get A or B or (C and D), but you want (A or B or C) and D
来源：https://stackoverflow.com/questions/11963564/get-back-the-same-result-when-trying-to-find-different-data