How Can I Efficiently Group MySQL Data by Week?

Grouping by Week in MySQL: Beyond DATE_FORMAT

Unlike Oracle's convenient TRUNC function, MySQL lacks a direct method to convert timestamps to the previous Sunday's midnight. To address this challenge, MySQL users must employ alternative techniques.

One approach is to combine the YEAR and WEEK functions, such as:

SELECT YEAR(timestamp), WEEK(timestamp), ...
FROM ...
GROUP BY YEAR(timestamp), WEEK(timestamp)

Another option is to utilize the YEARWEEK function, with an optional mode parameter to control how weeks that cross January 1st are handled.

SELECT YEARWEEK(mysqldatefield, mode) AS week, ...
FROM ...
GROUP BY week

By combining these date functions in a single expression, it is possible to obtain the desired week grouping:

SELECT YEAR(timestamp) || '/' || WEEK(timestamp) AS week, ...
FROM ...
GROUP BY week

For cases where incomplete weeks at the beginning or end of a year are undesirable, the YEAR/WEEK approach may be preferred. Alternatively, YEARWEEK can be used with mode set to 0 or 2 to group by complete weeks, including if they span January 1st.

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