Question

I’d like to have the week number and year, for a given date, from MySQL with the following rules:

• If the date is at the end of the year, but in the first week of the next year, I need to return 1 as the week number.
• If the date is at the beginning of the year, but in the last week of the previous year, I need to return 52 (or 53) as the week number.

I’ve read the week function in MySQL but I can’t get the result I want.

Date and Time Functions: WEEK(date[,mode])

I am on the french calendar, so I have to begin the week on Monday and week 1 is the first week with more than 3 days this year.

Therefore I can only use options 1 and 3.

When I write the following queries:

• select week (‘2012-12-31’, 3), the result is 1

• select week (‘2012-12-31’, 1), the result is 53

When I test on the 1st Jan 2016:

• select week (‘2016-1-1’, 3), the result is 53

• select week (‘2016-1-1’, 1), the result is 0

Option 1 can’t be used, because I can’t detect that 2012-12-31 is in the next year.

Option 3 can be used, but I have the add two pieces of logic: if weeknumber = 1 and month = 12, year + 1 and if weekumber = 53 and month = 1 then year – 1

Does someone have a better solution?

Regards

Answer 1

Ok, I think I get what you’re trying to do now.

As the documentation says:

We decided to return 0 instead because we want the function to return
“the week number in the given year.”

If you want the week number for the year that the week is in, they suggest using the YEARWEEK() function, which takes the same mode arguments as WEEK():

If you would prefer the result to be evaluated with respect to the
year that contains the first day of the week for the given date…
use the YEARWEEK() function:

 mysql> SELECT YEARWEEK('2000-01-01');
         -> 199952
 mysql> SELECT MID(YEARWEEK('2000-01-01'),5,2);
         -> '52'

So some examples of what you’d use:

mysql> SELECT MID(YEARWEEK('2012-1-1',3),5,2)
         -> '52'
mysql> SELECT MID(YEARWEEK('2012-12-31',3),5,2)
         -> '01'