Get start and end week date by month and year

Question

How I need the week is by this -- a week always starts on a sunday so for feburary it will be
start week end week
12-02-1 12-02-04
12-02-05 12-02-11
12-02-12 12-02-18
12-02-19 12-02-25
12-02-26 12-29-29
So because the first week does not start on a sunday it goes from
1(wednesday) to 4th(saturday) Just like a calendar.
Thanks in advance
so far from Solomons help I have this
This is for january
WITH t AS (
SELECT TRUNC(TRUNC(to_date('01-01-12','MM-DD-YY'),'YYYY') -1,'W') + (LEVEL-1 ) * 7 week_start_date
FROM DUAL
CONNECT BY LEVEL <= 53
SELECT week_start_date,
LEAST(LAST_DAY(to_date('01-01-12','MM-DD-YY')),week_start_date + 6) week_end_date
FROM t
WHERE week_start_date >= TRUNC(to_date('01-01-12','MM-DD-YY'),'MM')
AND week_start_date < ADD_MONTHS(TRUNC(to_date('01-01-12','MM-DD-YY'),'MM'),1)
start week end week
12-01-02     12-01-08
12-01-09     12-01-15
12-01-16     12-01-22
12-01-23     12-01-29
12-01-30     12-01-31

Answer 1

If week satrts Sunday:
WITH t AS (
           SELECT TRUNC(TRUNC(&dt,'MM') + 1,'IW') - 1 + (LEVEL - 1) * 7 week_start_date
            FROM  DUAL
            CONNECT BY TRUNC(TRUNC(&dt,'MM') + 1,'IW') - 1 + (LEVEL - 1) * 7 <= LAST_DAY(&dt)
SELECT  GREATEST(week_start_date,TRUNC(&dt,'MM')) week_start_date,
        LEAST(LAST_DAY(&dt),week_start_date + 6) week_end_date
  FROM  t
  WHERE week_start_date <= LAST_DAY(&dt)
/For example:
SQL> SET VERIFY OFF
SQL> DEFINE dt="DATE '2012-01-17'" -- January
SQL> WITH t AS (
  2             SELECT TRUNC(TRUNC(&dt,'MM') + 1,'IW') - 1 + (LEVEL - 1) * 7 week_start_date
  3              FROM  DUAL
  4              CONNECT BY TRUNC(TRUNC(&dt,'MM') + 1,'IW') - 1 + (LEVEL - 1) * 7 <= LAST_DAY(&dt)
  5            )
  6  SELECT  GREATEST(week_start_date,TRUNC(&dt,'MM')) week_start_date,
  7          LEAST(LAST_DAY(&dt),week_start_date + 6) week_end_date
  8    FROM  t
  9    WHERE week_start_date <= LAST_DAY(&dt)
10  /
WEEK_STAR WEEK_END_
01-JAN-12 07-JAN-12
08-JAN-12 14-JAN-12
15-JAN-12 21-JAN-12
22-JAN-12 28-JAN-12
29-JAN-12 31-JAN-12
SQL> SET VERIFY OFF
SQL> DEFINE dt="DATE '2012-02-25'" -- February
SQL> WITH t AS (
  2             SELECT TRUNC(TRUNC(&dt,'MM') + 1,'IW') - 1 + (LEVEL - 1) * 7 week_start_date
  3              FROM  DUAL
  4              CONNECT BY TRUNC(TRUNC(&dt,'MM') + 1,'IW') - 1 + (LEVEL - 1) * 7 <= LAST_DAY(&dt)
  5            )
  6  SELECT  GREATEST(week_start_date,TRUNC(&dt,'MM')) week_start_date,
  7          LEAST(LAST_DAY(&dt),week_start_date + 6) week_end_date
  8    FROM  t
  9    WHERE week_start_date <= LAST_DAY(&dt)
10  /
WEEK_STAR WEEK_END_
01-FEB-12 04-FEB-12
05-FEB-12 11-FEB-12
12-FEB-12 18-FEB-12
19-FEB-12 25-FEB-12
26-FEB-12 29-FEB-12
SQL> SET VERIFY OFF
SQL> DEFINE dt="DATE '2012-03-07'" -- March
SQL> WITH t AS (
  2             SELECT TRUNC(TRUNC(&dt,'MM') + 1,'IW') - 1 + (LEVEL - 1) * 7 week_start_date
  3              FROM  DUAL
  4              CONNECT BY TRUNC(TRUNC(&dt,'MM') + 1,'IW') - 1 + (LEVEL - 1) * 7 <= LAST_DAY(&dt)
  5            )
  6  SELECT  GREATEST(week_start_date,TRUNC(&dt,'MM')) week_start_date,
  7          LEAST(LAST_DAY(&dt),week_start_date + 6) week_end_date
  8    FROM  t
  9    WHERE week_start_date <= LAST_DAY(&dt)
10  /
WEEK_STAR WEEK_END_
01-MAR-12 03-MAR-12
04-MAR-12 10-MAR-12
11-MAR-12 17-MAR-12
18-MAR-12 24-MAR-12
25-MAR-12 31-MAR-12
SQL> SY.
Edited by: Solomon Yakobson on Jan 12, 2012 1:19 PM