Comparing Selected Date Range With Current & Previous Month

Question

I would like to provide the user to option to select a range of date in current month and results should be comparison of same date range for current & previous month. Eg. selected date 1-12-2022 to 15-12-2022 Result:

Count X 1-11-2022 to 15-11-2022
Count X 1-12-200 to 15-12-2022

Can this be achieved through date_part function?

Answer 1

Suppose you have a column with type date named ts in your table:

SELECT
    count(*) FILTER ( WHERE ts BETWEEN cast(:lower AS DATE) - INTERVAL '1 month' AND cast(:upper AS DATE) - INTERVAL '1 month') previous,
    count(*) FILTER ( WHERE ts BETWEEN cast(:lower AS DATE) AND cast(:upper AS DATE) ) selected,
    count(*) FILTER ( WHERE ts BETWEEN cast(:lower AS DATE) + INTERVAL '1 month' AND cast(:upper AS DATE) + INTERVAL '1 month' ) next
FROM your_table;

You just need to provide the lower and upper bound values as dates (eg '01-12-2022'. This will give you 3 columns -- previous , selected and next -- with the corresponding row-counts. BTW: the upper bound is exclusive.