How to find the 1st sunday in a month

Question

v_end := '01-nov-' || in_year;
v_sql_text := 'select next_day('''||v_end||''',''sunday'')+7 from dual';
this works except that nov 1st is a sunday. better idea?

Answer 1

Warren, besides being a big overkill (comparing to NEXT_DATE solution), it is, same as NEXT_DAY solution, NLS dependent. Assume you have a client in Germany:
SQL> alter session set nls_date_language=german;
Session altered.
SQL> select next_day(sysdate,'SUNDAY') from dual;
select next_day(sysdate,'SUNDAY') from dual
ERROR at line 1:
ORA-01846: not a valid day of the week
SQL> NLS independent solution I am aware of is based on Julian date 1 being Tuesday and therefore Julian date 6 being SUnday:
SQL> select to_char(to_date('1','J'),'Day') from dual;
TO_CHAR(T
Tuesday
SQL> select to_char(to_date('6','J'),'Day') from dual;
TO_CHAR(T
Sunday
SQL> Therefore, NLS independent first Sunday of the month is:
SQL> alter session set nls_date_format='FMDay, Month DD YYYY';
Session altered.
SQL> alter session set nls_date_language=american;
Session altered.
SQL> SELECT NEXT_DAY(
  2                  TRUNC(SYSDATE, 'MM') - 1,
  3                  to_char(to_date('6','J'),'Day')
  4                 )
  5    FROM dual
  6  /
NEXT_DAY(TRUNC(SYSDATE,'MM')
Sunday, February 4 2007
SQL> alter session set nls_date_language=german;
Session altered.
SQL> SELECT NEXT_DAY(
  2                  TRUNC(SYSDATE, 'MM') - 1,
  3                  to_char(to_date('6','J'),'Day')
  4                 )
  5    FROM dual
  6  /
NEXT_DAY(TRUNC(SYSDATE,'MM')-
Sonntag, Februar 4 2007
SQL> alter session set nls_date_language=french;
Session altered.
SQL> SELECT NEXT_DAY(
  2                  TRUNC(SYSDATE, 'MM') - 1,
  3                  to_char(to_date('6','J'),'Day')
  4                 )
  5    FROM dual
  6  /
NEXT_DAY(TRUNC(SYSDATE,'MM'
Dimanche, Février 4 2007
SQL> SY.