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postgresql - How to get the count of current month Sunday's in psql?

How to get total number of Sunday's for given date in postgresql

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You need EXTRACT:

SELECT 
    EXTRACT(DOW FROM DATE '2011-02-16') = 0; -- 0 is Sunday

This can result in true or false, it's a sunday or it's not. I have no idea what you mean by "total number" because that will always be 0 (the date is not a sunday) or 1 (the given data is a sunday).

Edit: Something like this?

SELECT 
    COUNT(*)
FROM
    generate_series(timestamp '2011-01-01', '2011-03-01', '1 day') AS g(mydate)
WHERE
    EXTRACT(DOW FROM mydate) = 0;

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