Hello Dev, have you ever found yourself struggling with SQL Server date time format? Do you want to learn how to work with date and time data in SQL Server more efficiently? You’ve come to the right place! In this article, we will provide you with a complete guide that covers everything you need to know about SQL Server date time format.
Introduction to SQL Server Date Time Format
Working with date and time data in SQL Server can be challenging, especially for beginners. SQL Server date time format is a complex topic that requires a good understanding of the different data types, functions, and operators used in SQL Server. In this section, we will introduce you to the basics of SQL Server date time format.
SQL Server Date Time Data Types: SQL Server supports several data types for storing date and time data, including DATE, TIME, DATETIME, SMALLDATETIME, DATETIME2, and DATETIMEOFFSET.
SQL Server Date Time Functions: SQL Server provides a wide range of functions that can be used for working with date and time data. Some of the most commonly used functions include DATEADD, DATEDIFF, GETDATE, YEAR, MONTH, DAY, and more.
SQL Server Date Time Operators: SQL Server also supports several operators that can be used for working with date and time data, including +, -, <, >, <=, >=, =, and more.
Now that you have a basic understanding of SQL Server date time format, let’s dive deeper into some of the most important concepts.
Working with Date and Time Data in SQL Server
SQL Server Date Time Data Types
As we mentioned earlier, SQL Server supports several data types for storing date and time data. Let’s take a closer look at each data type:
Data Type |
Description |
|---|---|
DATE |
Stores only the date without the time |
TIME |
Stores only the time without the date |
DATETIME |
Stores both the date and time with a precision of up to 3.33 milliseconds |
SMALLDATETIME |
Stores both the date and time with a precision of up to one minute |
DATETIME2 |
Stores both the date and time with a precision of up to 100 nanoseconds |
DATETIMEOFFSET |
Stores both the date and time with an offset from UTC time |
When choosing a date time data type in SQL Server, you should consider the precision and range of the data you need to store. For example, if you only need to store the date, you can use the DATE data type, which takes up less space than the DATETIME data type.
SQL Server Date Time Functions
SQL Server provides many functions that can be used for working with date and time data. Here are some of the most commonly used functions:
- DATEADD: Adds a specified number of intervals to a date or time value
- DATEDIFF: Returns the difference between two dates or times
- GETDATE: Returns the current date and time
- YEAR: Returns the year of a specified date or time value
- MONTH: Returns the month of a specified date or time value
- DAY: Returns the day of a specified date or time value
You can find a full list of SQL Server date time functions in the official Microsoft documentation.
SQL Server Date Time Operators
SQL Server supports several operators that can be used for working with date and time data. Here are some of the most commonly used operators:
- +: Adds a specified number of days to a date value
- -: Subtracts a specified number of days from a date value
- <: Compares two date or time values to check if the first is earlier than the second
- :>: Compares two date or time values to check if the first is later than the second
- <=: Compares two date or time values to check if the first is earlier than or equal to the second
- :>=: Compares two date or time values to check if the first is later than or equal to the second
- =: Compares two date or time values to check if they are equal
Now that you have a good understanding of SQL Server date time data types, functions, and operators, let’s move on to some practical examples.
SQL Server Date Time Examples
Example 1: Converting a String to a Date
Let’s say you have a string value that represents a date, but you need to convert it to a valid date data type in SQL Server. Here is an example:
DECLARE @DateString VARCHAR(50) = '2022-01-01';DECLARE @Date DATE;SET @Date = CONVERT(DATE, @DateString);
In this example, we declare a variable called @DateString and assign it a string value that represents a date. We also declare another variable called @Date and set it to the result of the CONVERT function, which converts the @DateString value to a valid DATE data type.
Example 2: Calculating the Age of a Person
Let’s say you have a table that stores information about people, including their date of birth. You want to calculate the age of each person in the table. Here is an example:
SELECT FirstName, LastName, DateOfBirth, DATEDIFF(YEAR, DateOfBirth, GETDATE()) AS AgeFROM People;
In this example, we use the DATEDIFF function to calculate the difference between the DateOfBirth value and the current date and time, in years. We also use the GETDATE function to get the current date and time.
Example 3: Formatting a Date Time Value
Let’s say you have a DATETIME value and you want to format it in a specific way. Here is an example:
DECLARE @DateTime DATETIME = '2022-01-01 12:30:00';SELECT CONVERT(VARCHAR(50), @DateTime, 101) AS FormattedDateTime;
In this example, we declare a variable called @DateTime and set it to a specific DATETIME value. We also use the CONVERT function to format the @DateTime value as a string in the format ‘mm/dd/yyyy’. You can find a full list of available date time formats in the official Microsoft documentation.
SQL Server Date Time FAQ
What is the default date time format in SQL Server?
The default date time format in SQL Server is ‘yyyy-mm-dd hh:mi:ss.mmm’. This format is used by many built-in functions and operators in SQL Server.
What is the difference between the DATETIME and DATETIME2 data types?
The DATETIME2 data type is an improvement over the DATETIME data type, as it provides a higher precision and a wider range of supported values. The DATETIME2 data type can store up to 7 decimal places for seconds, compared to 3 decimal places for the DATETIME data type.
How can I convert a DATETIME value to a Unix timestamp?
DECLARE @DateTime DATETIME = '2022-01-01 12:30:00';SELECT DATEDIFF(SECOND, '1970-01-01 00:00:00', @DateTime) AS UnixTimestamp;
In this example, we use the DATEDIFF function to calculate the difference between the @DateTime value and the Unix epoch (January 1st, 1970 at 00:00:00), in seconds.
How can I get the first day of the month in SQL Server?
DECLARE @Date DATE = '2022-01-15';SELECT DATEADD(MONTH, DATEDIFF(MONTH, 0, @Date), 0) AS FirstDayOfMonth;
In this example, we use the DATEADD function to add a specific number of months to the ‘0’ date (which represents January 1st, 1900), based on the difference between the @Date value and the ‘0’ date, in months. This will give us the first day of the month of the @Date value.
How can I get the last day of the month in SQL Server?
DECLARE @Date DATE = '2022-01-15';SELECT DATEADD(MONTH, DATEDIFF(MONTH, 0, @Date) + 1, 0) - 1 AS LastDayOfMonth;
In this example, we use the DATEADD function to add a specific number of months to the ‘0’ date, based on the difference between the @Date value and the ‘0’ date, in months, plus 1. This will give us the first day of the next month. We then subtract one day from this value to get the last day of the current month.
Conclusion
Working with date and time data in SQL Server can be challenging, but with the right knowledge and tools, you can master this topic and become a more efficient SQL developer. In this article, we provided you with a comprehensive guide that covers everything you need to know about SQL Server date time format, including data types, functions, operators, practical examples, and FAQs.
We hope this article has been helpful to you and that you can apply these concepts in your own SQL projects. Happy coding!