In Oracle and MariaDB, LAST_DAY function returns the date of the last day of the month for the specified datetime expression.
Note that Oracle LAST_DAY returns the DATE data type that includes both date and time, while MariaDB LAST_DAY returns the DATE data type that includes the date part only (year, month and day).
Oracle:
ALTER SESSION SET NLS_DATE_FORMAT = 'YYYY-MM-DD HH24:MI:SS'; -- Returns last day of May -- Note that the time part remained unchanged SELECT LAST_DAY(TIMESTAMP '2021-05-25 23:18:13') FROM dual; # 2021-05-31 23:18:13
MariaDB - Oracle Compatibility:
-- Returns last day of May -- Note that the time part was removed SELECT LAST_DAY(TIMESTAMP '2021-05-25 23:18:13'); # 2021-05-31
Although MariaDB has the LAST_DAY function you still may need to convert arithmetic expressions involving the function, for example:
Oracle:
-- Get the first day of the next month SELECT LAST_DAY(SYSDATE) + 1 FROM dual; # 2021-06-01 17:43:27
You cannot use LAST_DAY() + 1 for the same purpose in MariaDB, you have to use DATE_ADD function:
MariaDB - Oracle Compatibility:
-- Arithmetics expression + 1 produces an integer result SELECT LAST_DAY(SYSDATE()) + 1; # 20210532 -- Use DATE_ADD to get the correct result SELECT DATE_ADD(LAST_DAY(SYSDATE()), INTERVAL 1 DAY); # 2021-06-01
For more information, see Oracle to MariaDB Migration - Oracle Compatibility Mode.