How to get same day of a month in every year in the DB ( To update a flag )

Question

Hi,
I am trying to formulate an update query for a flag table in our database which contains dates, and flag columns. Currently the system have dates for the next ten years. The flags are updated with values 0 or 1 if a particular date falls under the required criteria.
I need to update flag column for the same day of the month in every year. e.g. 2nd Sunday of October. The value should be updated to all years in the table. Currently I am using the following query to update the current year.
UPDATE FILTERCALENDAR SET YEAR_WINDOW=1 WHERE c_date = NEXT_DAY( TO_DATE('OCT-2013','MON-YYYY'), 'SUNDAY') + (2-1)*7;
and for next year Like
UPDATE FILTERCALENDAR SET YEAR_WINDOW=1 WHERE c_date = add_months(NEXT_DAY( TO_DATE('OCT-2013','MON-YYYY'), 'SUNDAY') + (2-1)*7,+12)-1;
This is not an excellent way to do it as it does not take care of leap years and it does not scan and update values in the whole table for all years correctly.
Can any one help me to resolve this please.

Answer 1

Hi,
user10903866 wrote:
Hi,
I am trying to formulate an update query for a flag table in our database which contains dates, and flag columns. Currently the system have dates for the next ten years. The flags are updated with values 0 or 1 if a particular date falls under the required criteria.
I need to update flag column for the same day of the month in every year. e.g. 2nd Sunday of October. The value should be updated to all years in the table. Currently I am using the following query to update the current year.
UPDATE FILTERCALENDAR SET YEAR_WINDOW=1 WHERE c_date = NEXT_DAY( TO_DATE('OCT-2013','MON-YYYY'), 'SUNDAY') + (2-1)*7;That's the 2nd Sunday after October 1; the 2nd Sunday of October is the 2nd Sunday after September 30, so you need to subtract 1 more day before calling NEXT_DAY.
I'd do it this way:
WHERE   c_date = NEXT_DAY ( TO_DATE ( '01-OCT-2013', 'DD-MON-YYYY') - 8
                         , 'SUNDAY'
                 ) + (7 * 2)     -- Last number is week numberRemember, calling NEXT_DAY like this depends on your NLS_DATE_LANGUAGE.
and for next year Like
UPDATE FILTERCALENDAR SET YEAR_WINDOW=1 WHERE c_date = add_months(NEXT_DAY( TO_DATE('OCT-2013','MON-YYYY'), 'SUNDAY') + (2-1)*7,+12)-1;If you want the 2nd Sunday in October, 2014, then take the previous expression, and just change 2013 to 2014:
WHERE   c_date = NEXT_DAY ( TO_DATE ( '01-OCT-2014'     -- or any month and year you want
                                    , 'DD-MON-YYYY'
                        ) - 8
                         , 'SUNDAY'
                 ) + (7 * 2)     -- Last number is week number
This is not an excellent way to do it as it does not take care of leap years and it does not scan and update values in the whole table for all years correctly.
Can any one help me to resolve this please. 
I hope this answers your question.
If not, post a little sample data (CREATE TABLE and INSERT statements, relevant columns only) for all the tables involved, and the results you want from that data.
In the case of a DML operation (such as UPDATE) the sample data should show what the tables are like before the DML, and the results will be the contents of the changed table(s) after the DML.
Explain, using specific examples, how you get those results from that data.
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