get week number from date into dropdownlist - asp.net

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;

Answer 2

In your on load event, or wherever you want, you will put this VBA code
Me!myCombo.RowSource = "yourquerytexthere;"
(Or whatever query you go with..probably whichever one you're using from your last question that Remou answered for you).
I think in this question, you already know what you want to query, you are just asking about setting the control.
That code is just
Me!myCombo.RowSource = "yourquerystring"
like
Me!myCombo.RowSource = "SELECT distinct datepart("ww", dates) FROM yourtable;"
Where Me!myCombo is the name of your combobox.

Answer 3

Annual ISO week# table - Oracle SQL query:
-- ISO_WK# --
SELECT mydate
, TRUNC(mydate, 'w') wk_starts
, TRUNC(mydate, 'w') + 7 - 1/86400 wk_ends
, TO_NUMBER (TO_CHAR (mydate, 'IW')) ISO_WK#
FROM
(
SELECT TRUNC(SYSDATE, 'YEAR')-1 + LEVEL AS mydate
FROM dual
CONNECT BY LEVEL <=
(-- First day of curr year - first day of past year --
SELECT TRUNC(SYSDATE, 'YEAR')-TRUNC(ADD_MONTHS (SYSDATE, -12), 'YEAR') "Num of Days"
FROM dual
)
)
/