First Day of Week is set to Sunday instead of Monday in Oracle

Question

I have the following query:

SELECT forecastDate, to_char(to_date(forecastDate),'WW') AS WEEK_NUMBER
FROM ACT_FORECAST

Which give me this result :

forecastDate | WEEK_NUMBER
14/07/2017     28
15/07/2017     28
16/07/2017     29

But in my region the week start on Monday, I should have 28 for the 16/07/2017.

The NLS_TERRITORY value of my DB is 'France'.

I tried multiple things but nothing worked.

Any ideas?

Thanks

Answer 1

Reason is the format WW where documentation says:

WW

Week of year (1-53) where week 1 starts on the first day of the year and continues to the seventh day of the year.

Luckily on ISO-8601 the first day of week is also Monday, so you can use

SELECT forecastDate, to_char(to_date(forecastDate),'IW') AS WEEK_NUMBER
FROM ACT_FORECAST

IW

Calendar week of year (1-52 or 1-53), as defined by the ISO 8601 standard.

• A calendar week starts on Monday.

• The first calendar week of the year includes January 4.

• The first calendar week of the year may include December 29, 30 and 31.

• The last calendar week of the year may include January 1, 2, and 3.

And btw, you should change the data type of column forecastDate to DATE or TIMESTAMP .