SQL中如何将年周转为年月日？

Question

Is there an efficient way or function to convert the week of the year to a datetime object? For example, if I had "2018-03", how would I be able to convert it to "2018-01-21"? (The third week of the year would correspond to the third week of the year, January 21st).

Any help is appreciated. Thank you in advance!

Answer 1

consider below as an option

select year_week, 
  date_add(
    date(cast(split(year_week, '-')[offset(0)] as int64), 1, 1),
    interval cast(split(year_week, '-')[offset(1)] as int64) * 7 - 1 day
  ) date
from data      

if applied to sample data in your question - output is