The LAST_DAY function is part of date functions in the Oracle PL/SQL language that helps developers determine the last day of a specified month. This function is particularly useful in financial applications, where it is essential to calculate the last day of a month for various accounting purposes.


The syntax of the LAST_DAY function is as follows:


The LAST_DAY function accepts a date or timestamp as an input and returns the last day of the month in which the input date falls. The returned value is always a date datatype and is expressed in the format “DD-MON-YYYY”.


Here is an example of how the LAST_DAY function can be used:

LAST_DAY('01-APR-2023') AS last_day_of_month
FROM dual;

This query returns the value “30-APR-2023”, which is the last day of the month of April 2023.

In addition to using the LAST_DAY function with a hardcoded date value, you can also use it with a column or variable that contains a date datatype. For example:

date_var DATE := '15-MAR-2023';
last_day_of_month DATE;
last_day_of_month := LAST_DAY(date_var);
DBMS_OUTPUT.PUT_LINE('The last day of the month is: ' || last_day_of_month);

In this PL/SQL block, the LAST_DAY function is used to determine the last day of the month for the date stored in the “date_var” variable. The output of this block would be “The last day of the month is: 31-MAR-2023”.

In summary, the LAST_DAY function is a valuable tool for Oracle PL/SQL developers who need to work with dates and times. It simplifies the process of determining the last day of a month, and it can be used with both hardcoded date values and variables that contain date datatypes.