Current Date SQL Server: Everything Devs Need to Know

Dear Dev, welcome to our comprehensive guide on the current date in SQL Server. As you may know, the current date is a crucial aspect of any database system, and it can have a significant impact on your daily operations. Whether you are a seasoned SQL Server developer or just starting, this article will provide you with all the essential information you need to know about the current date in SQL Server.

What is the Current Date in SQL Server?

In SQL Server, the current date represents the system date and time on which the instance of SQL Server is running. It is a system function that returns the current date and time.

The current date in SQL Server is essential for many reasons, such as:

• Tracking changes made to your data
• Filtering and sorting data
• Calculating the age of records
• Managing tasks based on specific dates

How to Get the Current Date in SQL Server

To get the current date in SQL Server, you can use the built-in GETDATE() function. This function returns the current date and time in SQL Server’s default format.

For example, you can use the following query to get the current date and time:

Query	Result
SELECT GETDATE()	2022-01-26 08:30:00.000

The GETDATE() function is a non-deterministic function, which means that it returns a different value every time you execute it. Therefore, you cannot use this function in a computed column or a check constraint.

How to Get the Current Date Only in SQL Server

If you want to get the current date only without the time component, you can use the CAST() function to convert the current date and time to a date data type.

For example, you can use the following query to get the current date only:

Query	Result
SELECT CAST(GETDATE() AS DATE)	2022-01-26

The CAST() function converts the current date and time to a date data type, which removes the time component from the result.

How to Use the Current Date in SQL Server

Filtering Data by Date

You can use the current date to filter data by date. For example, you can retrieve all records that were created today or within a specific range of dates.

For example, you can use the following query to retrieve all records created today:

Query	Result
SELECT * FROM MyTable WHERE CreatedDate = CAST(GETDATE() AS DATE)	Returns all records created today

In this example, we used the CAST() function to get the current date only, and then filtered the records in MyTable by the CreatedDate column.

Calculating the Age of Records

You can also use the current date to calculate the age of records in your database. For example, you can calculate the age of a customer’s account or the number of days since the last login.

For example, you can use the following query to calculate the age of a record:

Query	Result
SELECT DATEDIFF(YEAR, BirthDate, GETDATE()) AS Age FROM Customers WHERE CustomerID = 1	Returns the age of the customer with ID 1

In this example, we used the DATEDIFF() function to calculate the number of years between the customer’s birth date and the current date. We also filtered the results by the CustomerID column in the Customers table.

FAQs

What is the Difference Between GETDATE() and SYSDATETIME()?

GETDATE() and SYSDATETIME() are both system functions that return the current date and time in SQL Server. The main difference between them is the data type they return.

GETDATE() returns a DATETIME data type, which has a precision of 3. This means that the time component has a resolution of 1/300th of a second.

SYSDATETIME() returns a DATETIME2 data type, which has a higher precision of up to 7 decimal places. This means that the time component has a resolution of 100 nanoseconds.

Can I Modify the Current Date in SQL Server?

No, you cannot modify the current date in SQL Server. The current date is a read-only system function that returns the date and time on which the instance of SQL Server is running.

Can I Use the Current Date in a Computed Column?

No, you cannot use the GETDATE() function in a computed column. The reason for this is that the GETDATE() function is a non-deterministic function, which means that it returns a different value every time it is called. Computed columns must be deterministic, which means that they always return the same value for a given input.

Can I Use the Current Date in a Check Constraint?

No, you cannot use the GETDATE() function in a check constraint for the same reason as above. Check constraints must be deterministic and always return the same value for a given input.

Can I Change the Default Format of the Current Date?

Yes, you can change the default format of the current date and time in SQL Server by using the CONVERT() function. This function allows you to convert the date and time to a specific format.

For example, you can use the following query to convert the current date and time to a custom format:

Query	Result
SELECT CONVERT(VARCHAR(20), GETDATE(), 100)	Returns the current date and time in the format ‘Mon dd yyyy hh:miAM (or PM)’

In this example, we used the CONVERT() function to convert the current date and time to the ‘Mon dd yyyy hh:miAM (or PM)’ format. The VARCHAR(20) parameter specifies the maximum length of the output string.

Conclusion

Now that you have learned everything about the current date in SQL Server, you can use this knowledge to improve your database operations and create more efficient queries. Remember to always use the correct data types and follow best practices when working with dates in SQL Server.