Hello and welcome to this journal article on date functions in SQL Server. SQL Server is a relational database management system created by Microsoft Corporation. It is used to store, manage and retrieve data efficiently. One of the primary uses of SQL Server is in the development of web applications. Date functions in SQL Server play an important role in web development as they allow developers to extract and manipulate data related to dates and times easily.
The Basic Date and Time Functions
In SQL Server, there are several basic date and time functions that you can use to manipulate date and time values. These functions take a date or time value as input and return a date or time value as output. The following are the basic date and time functions in SQL Server:
| Function | Description |
|---|---|
| GETDATE() | Returns the current system date and time |
| DATEADD() | Adds or subtracts a specified time interval from a date or time value |
| DATEDIFF() | Returns the difference between two dates or times |
| DATEPART() | Returns a specific part of a date or time value, such as the year, month or day |
GETDATE() Function
The GETDATE() function is used to get the current system date and time. It returns a datetime value. This function is commonly used to insert the current date and time into a table:
INSERT INTO Orders (OrderDate)
VALUES (GETDATE())You can also use the GETDATE() function in a SELECT statement:
SELECT GETDATE()DATEADD() Function
The DATEADD() function is used to add or subtract a specified time interval from a date or time value. The syntax of the DATEADD() function is as follows:
DATEADD(interval, number, date)The interval argument specifies the time interval to add or subtract. The number argument specifies the number of intervals to add or subtract. The date argument is the date or time value to which the interval is added or subtracted.
For example, to add 10 days to the current date, you can use the following query:
SELECT DATEADD(day, 10, GETDATE())DATEDIFF() Function
The DATEDIFF() function is used to calculate the difference between two dates or times. The syntax of the DATEDIFF() function is as follows:
DATEDIFF(interval, startdate, enddate)The interval argument specifies the time interval to calculate the difference. The startdate argument is the starting date or time value, and the enddate argument is the ending date or time value.
For example, to calculate the number of days between two dates, you can use the following query:
SELECT DATEDIFF(day, '2021-01-01', '2021-01-10')DATEPART() Function
The DATEPART() function is used to extract a specific part of a date or time value, such as the year, month or day. The syntax of the DATEPART() function is as follows:
DATEPART(interval, date)The interval argument specifies the date or time interval to extract, and the date argument is the date or time value from which to extract the interval.
For example, to extract the year from a date, you can use the following query:
SELECT DATEPART(year, '2021-01-01')Advanced Date and Time Functions
SQL Server also provides advanced date and time functions that are useful in specific situations. The following are the advanced date and time functions in SQL Server:
| Function | Description |
|---|---|
| DATEDIFF_BIG() | Returns the difference between two dates or times in a specified time unit |
| DATEFROMPARTS() | Returns a date value from the specified year, month and day values |
| DATEPART_BIG() | Returns a specific part of a date or time value in a big integer format |
| EOMONTH() | Returns the last day of the month for the specified date value |
| SWITCHOFFSET() | Changes the time zone offset of a datetimeoffset value to a new offset |
DATEDIFF_BIG() Function
The DATEDIFF_BIG() function is similar to the DATEDIFF() function but returns the difference between two dates or times in a specified time unit in a big integer format. The syntax of the DATEDIFF_BIG() function is as follows:
DATEDIFF_BIG(interval, startdate, enddate)The interval argument specifies the time interval to calculate the difference, and the startdate argument is the starting date or time value, and the enddate argument is the ending date or time value.
For example, to calculate the number of seconds between two dates, you can use the following query:
SELECT DATEDIFF_BIG(second, '2021-01-01', '2021-01-10')DATEFROMPARTS() Function
The DATEFROMPARTS() function is used to create a date value from the specified year, month and day values. The syntax of the DATEFROMPARTS() function is as follows:
DATEFROMPARTS(year, month, day)The year, month and day arguments are the year, month and day values for which the date value is to be created.
For example, to create a date value for January 1, 2021, you can use the following query:
SELECT DATEFROMPARTS(2021, 1, 1)DATEPART_BIG() Function
The DATEPART_BIG() function is similar to the DATEPART() function but returns a specific part of a date or time value in a big integer format. The syntax of the DATEPART_BIG() function is as follows:
DATEPART_BIG(interval, date)The interval argument specifies the date or time interval to extract, and the date argument is the date or time value from which to extract the interval.
For example, to extract the year from a date in a big integer format, you can use the following query:
SELECT DATEPART_BIG(year, '2021-01-01')EOMONTH() Function
The EOMONTH() function is used to return the last day of the month for the specified date value. The syntax of the EOMONTH() function is as follows:
EOMONTH(date)The date argument is the date value for which the last day of the month is to be returned.
For example, to return the last day of January 2021, you can use the following query:
SELECT EOMONTH('2021-01-01')SWITCHOFFSET() Function
The SWITCHOFFSET() function is used to change the time zone offset of a datetimeoffset value to a new offset. The syntax of the SWITCHOFFSET() function is as follows:
SWITCHOFFSET(datetimeoffset, new_offset)The datetimeoffset argument is the datetimeoffset value for which the offset is to be changed, and the new_offset argument is the new offset to which the datetimeoffset value is to be changed.
For example, to change the time zone offset of a datetimeoffset value to the Eastern Time zone (UTC-05:00), you can use the following query:
SELECT SWITCHOFFSET('2021-01-01 12:00:00 -06:00', '-05:00')Frequently Asked Questions
What is SQL Server?
SQL Server is a relational database management system created by Microsoft Corporation.
What are date functions in SQL Server?
Date functions in SQL Server allow developers to extract and manipulate data related to dates and times easily.
What are the basic date and time functions in SQL Server?
The basic date and time functions in SQL Server are GETDATE(), DATEADD(), DATEDIFF() and DATEPART().
What are the advanced date and time functions in SQL Server?
The advanced date and time functions in SQL Server are DATEDIFF_BIG(), DATEFROMPARTS(), DATEPART_BIG(), EOMONTH() and SWITCHOFFSET().
How can I add 10 days to the current date in SQL Server?
You can add 10 days to the current date in SQL Server using the DATEADD() function as follows:
SELECT DATEADD(day, 10, GETDATE())How can I calculate the number of days between two dates in SQL Server?
You can calculate the number of days between two dates in SQL Server using the DATEDIFF() function as follows:
SELECT DATEDIFF(day, startdate, enddate)How can I extract the year from a date in SQL Server?
You can extract the year from a date in SQL Server using the DATEPART() function as follows:
SELECT DATEPART(year, date)How can I create a date value from the year, month and day values in SQL Server?
You can create a date value from the year, month and day values in SQL Server using the DATEFROMPARTS() function as follows:
SELECT DATEFROMPARTS(year, month, day)How can I change the time zone offset of a datetimeoffset value in SQL Server?
You can change the time zone offset of a datetimeoffset value in SQL Server using the SWITCHOFFSET() function as follows:
SELECT SWITCHOFFSET(datetimeoffset, new_offset)Conclusion
In conclusion, date functions in SQL Server are essential for manipulating and managing date and time values in web development. The basic date and time functions in SQL Server are GETDATE(), DATEADD(), DATEDIFF() and DATEPART(). SQL Server also provides advanced date and time functions such as DATEDIFF_BIG(), DATEFROMPARTS(), DATEPART_BIG(), EOMONTH() and SWITCHOFFSET() that are useful in specific situations. By mastering these functions, SQL Server developers can easily extract and manipulate data related to dates and times.