从一年中的当前一周减去一周

Question

I am trying to get one week earlier then current week of the year but my sql query is returning null. here is my query

select date_sub(yearweek('2014-01-01'),INTERVAL 1 week)

what is wrong with this query

Answer 1

If you want to get YEARWEEK of week prior to date, you can do this: Note: YEARWEEK results in 6-digit number, first 4 digits are week year, trailing 2 digits are week number.

SELECT YEARWEEK('2014-01-01' - INTERVAL 1 WEEK)

If you need to get a date that is one week before a given date, then:

SELECT '2014-01-01' - INTERVAL 1 WEEK

Answer 2

尝试这个

select date_sub(date('2014-01-01'),INTERVAL 1 week)

Answer 3

Try this:-

DATE_SUB(date('2014-01-01'), INTERVAL 7 DAY)

or

SELECT '2014-01-01' - INTERVAL 1 WEEK

Answer 4

The problem is that DATE_SUB takes a date as the first arguement, but year week returns yyyyww ie not a date. So this:

SELECT yearweek('2014-01-01');

Returns 201352 , this is then implicitly casted to a date, since it is not a date the result is null. You can replicate this by doing:

SELECT DATE(yearweek('2014-01-01'));

So if you subtract a week from NULL the result is also NULL .

The fix is to subtract the week first, then get the year week:

SELECT yearweek(date_sub('2014-01-01', INTERVAL 1 WEEK));

And the result is 201351 .

Answer 5

Are you looking for week number??? If yes then plz try this if it will work for you

Select DatePart(Week, Date add(day,-7,convert(date time,'01-jan-2014'))) 

Pleas let me know if you are looking for something else.

Answer 6

SELECT * FROM [table] WHERE WEEKOFYEAR(date) = WEEKOFYEAR(NOW()) - 1;