DAY (Transact-SQL)
Applies to: 
SQL Server
Azure SQL Database
Azure SQL Managed Instance
Azure Synapse Analytics
Analytics Platform System (PDW)
This function returns an integer that represents the day (day of the month) of the specified date.
See Date and Time Data Types and Functions (Transact-SQL) for an overview of all Transact-SQL date and time data types and functions.
Transact-SQL syntax conventions
Syntax
DAY ( date )
Arguments
date
An expression that resolves to one of the following data types:
- date
- datetime
- datetimeoffset
- datetime2
- smalldatetime
- time
For date, DAY will accept a column expression, expression, string literal, or user-defined variable.
Return Type
int
Return Value
DAY returns the same value as DATEPART (day, date).
If date contains only a time part, DAY will return 1 - the base day.
Examples
This statement returns 30 - the number of the day itself.
SELECT DAY('2015-04-30 01:01:01.1234567');
This statement returns 1900, 1, 1. The date argument has a number value of 0. SQL Server interprets 0 as January 1, 1900.
SELECT YEAR(0), MONTH(0), DAY(0);