Tip of the Day : Example Uses of the DAY Date Function

Welcome to SQL Server Helper !!!

This site is intended for those who are beginning to use SQL Server as part of their day-to-day activities.  You will find in this site a collection of useful functions, triggers, stored procedures and tips and tricks related to SQL Server.

Should you have any comments or questions regarding this site or if you want to ask SQL Server-related questions, e-mail us here.

We hope we are able to help and we are glad to help!!!

SQL Server Tip of the Day - March 26, 2023

Example Uses of the DAY Date Function

The DAY date function returns an integer representing the day DATEPART of the specified date.  This function is equivalent to DATEPART(DD, <date>).  The syntax of the DAY date function is as follows:

DAY ( <date> )

The <date> parameter is an expression of type DATETIME or SMALLDATETIME.

Here are a few uses of the DAY date function:

Usage #1 : Get Number of Days in a Month

SELECT DAY(DATEADD(MM, DATEDIFF(MM, 0, GETDATE()) + 1, 0) - 1) AS [Number of Days in the Month]

Usage #2: Determine if Today is the Last Day of the Month

SELECT CASE WHEN DAY(GETDATE()) > DAY(GETDATE() + 1)
            THEN 'Today is the last day of the month'
            ELSE 'Today is NOT the last day of the month' END AS [Last Day]

Usage #3 : Get the Last Day of the Previous Month

SELECT DATEADD(DD, -DAY(GETDATE()), GETDATE()) AS [Last Day of Previous Month With Time]
SELECT DATEADD(DD, DATEDIFF(DD, 0, GETDATE()),  -DAY(GETDATE())) AS [Last Day of Previous Month]

Usage #4 : Check for Holiday

SELECT CASE WHEN (MONTH(GETDATE()) = 7  AND DAY(GETDATE()) = 4 ) OR -- U.S. Independence Day
                 (MONTH(GETDATE()) = 1  AND DAY(GETDATE()) = 1 ) OR -- New Year's Day
                 (MONTH(GETDATE()) = 12 AND DAY(GETDATE()) = 25) OR -- Christmas Day
                 (MONTH(GETDATE()) = 11 AND DAY(GETDATE()) BETWEEN 22 AND 28
                                        AND DATENAME(DW, GETDATE()) = 'Thursday') OR -- Thanksgiving
                 (MONTH(GETDATE()) = 5  AND DAY(GETDATE()) BETWEEN 25 AND 31
                                        AND DATENAME(DW, GETDATE()) = 'Monday') OR -- Memorial Day
                 (MONTH(GETDATE()) = 9  AND DAY(GETDATE()) BETWEEN 1 AND 7
                                        AND DATENAME(DW, GETDATE()) = 'Monday') -- Labor Day
            THEN 'Holiday'
            ELSE 'Not a Holiday' END AS [Is US Holiday]

Usage #5 : Calculate the Average Daily Balance

SELECT [AggregateBalance] / DAY(GETDATE()) AS [Average Daily Balance]
FROM [dbo].[AccountBalance]

Usage #6 : Age Computation / Calculation

DECLARE @BirthDate    DATETIME = '1776/07/04'

SELECT YEAR(GETDATE()) - YEAR(@BirthDate) -
       CASE WHEN MONTH(GETDATE()) > MONTH(@BirthDate) OR
                (MONTH(GETDATE()) = MONTH(@BirthDate) AND
                 DAY(GETDATE())  >= DAY(@BirthDate))
            THEN 0 ELSE 1 END AS [Age of America]

Usage #7 : Format Date in YYYYMMDD Date Format

SELECT YEAR(GETDATE()) * 10000 + MONTH(GETDATE()) * 100 + DAY(GETDATE()) AS [YYYYMMDD]

SQL Server 2012

SQL Server 2008

User-Defined Functions

Date Functions

A collection of useful user-defined functions that deal with dates.

String Functions

A collection of useful user-defined functions that deal with strings (varchar/char/nvarchar/nchar).

Tree Functions

A collection of useful user-defined functions that deal with tree or hierarchical design structures.

Table-Valued Functions

A collection of useful table-valued user-defined functions that can be used to join with other tables.

SQL Server Built-in Functions

A reference to all built-in functions available within SQL Server grouped into categories.

Tips and Tricks

A collection of useful SQL Server-related tips and tricks:

SQL Server Error Messages

A list of SQL Server error messages and for certain error messages, discusses ways on how to solve the error or work around them:

Frequently Asked Questions