Return just the last day of each month with SQL

Question

I have a table that contains multiple records for each day of the month, over a number of years. Can someone help me out in writing a query that will only return the last d

Answer 1

Here's how I just solved this. day_date is the date field, calendar is the table that holds the dates.

SELECT cast(datepart(year, day_date) AS VARCHAR) 
+ '-' 
+ cast(datepart(month, day_date) AS VARCHAR) 
+ '-' 
+ cast(max(DATEPART(day, day_date)) AS VARCHAR) 'DATE'
FROM calendar
GROUP BY datepart(year, day_date)
    ,datepart(month, day_date)
ORDER BY 1

Answer 2

The easiest way I could find to identify if a date field in the table is the end of the month, is simply adding one day and checking if that day is 1.

where DAY(DATEADD(day, 1, AsOfDate)) = 1

If you use that as your condition (assuming AsOfDate is the date field you are looking for), then it will only returns records where AsOfDate is the last day of the month.

Answer 3

This should work on Oracle DB

select  distinct last_day(trunc(sysdate - rownum)) dt
    from dual
  connect by rownum < 430
   order by 1