WeekNumber to start of week date

[mdvreddy]

..

[mdvreddy]

yes. exactly correct.

[kezzemil]

Dears,
This is an old one, I know. But still I got some questions around it.
All the queries do use a date, either hardcoded or sysdate to do this calculation but, what if you do not have that ?
How can you do this if you have only a year and weeknumber, both in ISO-standard format (iyyy, iw)
How can you get the first day of the week let's say for 2015 01 (remember ISO-standard iyyy iw)
How can you get this one done with plain sql ?

Greetings, Patrick

P.S.: the answer should be : monday 29/12/2014