mySQL week function to match excel weeknum 16

Question

I am trying to figure out the syntax required to replicate the excel function of weeknum([date],16) that will achieve the same results in MySQL.

Currently, EXCEL WEEKNUM 16

=WEEKNUM(DATE(2021,1,1),16) = 1

but all of the week functions in MySQL cannot replicate this, I also tried

select week('2021-01-01', 0) from dual; result = 0
select week('2021-01-01', 1) from dual; result = 0
select week('2021-01-01', 2) from dual; result = 52
select week('2021-01-01', 3) from dual; result = 53
select week('2021-01-01', 4) from dual; result = 0
select week('2021-01-01', 5) from dual; result = 0
select week('2021-01-01', 6) from dual; result = 53
select week('2021-01-01', 7) from dual; result = 52

so as of now, my only option is to use CASE statements and manually +/- week numbers to match; however, this does not work for previous years when (again) trying to match to Excel WEEKNUM 16.

There is currently a question and answer on StackOverflow: MySQL week() Function to begin with Saturday asking the very same question; however, I have tried the solution presented and it does not work.

any help would be appreciated!

Answer 1

Yes as second parameters it only accepts numbers from 0 to 7

In Excel you can enter the days when the year starts but that is not like the standard works, but mysql folows the iso standard https://en.wikipedia.org/wiki/ISO_week_date

For that what you want you need a function

 SELECT WEEK( '2021-01-01', 0 )

 |  WEEK( '2021-01-01', 0 ) | |  -----------------------: |  |  0 | 

 SELECT WEEK( '2021-01-01', 1 )

 |  WEEK( '2021-01-01', 1 ) | |  -----------------------: |  |  0 | 

 SELECT WEEK( '2021-01-01', 2)

 |  WEEK( '2021-01-01', 2) | |  ----------------------: |  |  52 | 

 SELECT WEEK( '2021-01-01', 3 )

 |  WEEK( '2021-01-01', 3 ) | |  -----------------------: |  |  53 | 

 SELECT WEEK( '2021-01-01', 4 )

 |  WEEK( '2021-01-01', 4 ) | |  -----------------------: |  |  0 | 

 SELECT WEEK( '2021-01-01', 5 )

 |  WEEK( '2021-01-01', 5 ) | |  -----------------------: |  |  0 | 

 SELECT WEEK( '2021-01-01', 6 )

 |  WEEK( '2021-01-01', 6 ) | |  -----------------------: |  |  53 | 

 SELECT WEEK( '2021-01-01', 7 )

 |  WEEK( '2021-01-01', 7 ) | |  -----------------------: |  |  52 | 

db<>fiddle here