Question

I have a database table containing a row of dates in DateTime format. what I need to do is get all the distinct weeks numbers of the available dates. for example if I have the following dates:

03-JAN-13 
04-JAN-13
09-JAN-13

the sql query would give me the following weeks numbers: 1 and 2.
PS: afterwards I will put these values in a dropdownlist (no problem with that step).

So can anybody tell me how to do it?

Answer 1

You did not specify what RDBMS you are using but you could use the following to get week numbers.

SQL Server you would use DatePart():

select distinct datepart(week, dates) WeekNo
from yourtable

See SQL Fiddle with Demo

In MySQL you could use Week():

select distinct week(dates)
from yourtable

See SQL Fiddle with Demo

In Oracle, you could use to_char():

select distinct to_char(dates, 'W') WeekNo
from yourtable

See SQL Fiddle with Demo

In PostgreSQL you can use the following:

select distinct extract(WEEK from dates) WeekNO
from yourtable

See SQL Fiddle with Demo

Replace the yourtable with your table name and dates with your date column.

Edit #1: If you are using MS Access then you can still use DatePart() (this was tested in MS Access 2003):

SELECT distinct datepart("ww", dates) as WeekNo
FROM yourtable;