Question

I am trying to create a stored procedure that when given a month value, returns the user the last day of the month.

So far:

DROP PROCEDURE IF EXISTS getLastDayMonth$$
CREATE PROCEDURE getLastDayMonth(IN inMonth int) 
BEGIN
    SELECT LAST_DAY(inMonth);
END $$

I am having trouble figuring out how i can make inMonth a parameter that the sql function Last_DAY accepts. Is there another function that takes in an int as a month and returns the last day of the month? I am trying to avoid giving a DATE type as a paramater

Answer 1

You can add moths to first year day and get last_date:

SELECT LAST_DAY( DATE_ADD( '2012-01-01 00:00:00',  
                           INTERVAL inMonth - 1 MONTH) 
               );

Alternative solution is ELT function:

SELECT cast( 
         ELT(inmonth, '31', '28', '31', '30', '31', .... ,'31' )
         as SMALLINT 
       ) as last_day

The last one, use case statement:

SELECT case inmonth
        when 1 then 31
        when 2 then 29
        ...
        when 12 then 31
       end as last_day

EDITED

mysql> CREATE PROCEDURE getLastDayMonth(IN inMonth int)
    -> begin
    -> SET @t=inMonth -1;
    -> SELECT LAST_DAY( DATE_ADD( '2012-01-01 00:00:00',INTERVAL @t MONTH));
    -> end@@
Query OK, 0 rows affected (0.24 sec)