Hello Dev, welcome to this comprehensive guide on how to format date in SQL Server. Dates and times are essential to many applications, especially in business processes. Formatting dates in SQL Server can be a bit tricky, and it’s essential to get it right for data clarity and consistency. In this article, we’ll cover everything you need to know to master date formatting in SQL Server. Let’s dive in!
Understanding the Basics of Dates in SQL Server
Before we get into how to format dates in SQL Server, let’s briefly discuss how dates work in SQL Server. Dates in SQL Server are stored as the number of days since January 1, 1900, with January 1, 1900, being day 1. Time is stored as the fractional portion of a day, the decimal represents the time elapsed from midnight.
For example, if you see a date value of 44197.65625, this represents the date and time of September 13, 2020, at 3:45 PM (0.65625 * 24 hours = 15.75 hours = 3:45 PM).
Now that we know the basics of how dates are stored in SQL Server, let’s move on to how to format them.
The Convert Function in SQL Server
The CONVERT function in SQL Server is used to format dates from one format to another. It converts an expression from one data type to another data type. The syntax of the CONVERT function is as follows:
Function |
Description |
|---|---|
CONVERT(data_type(length),expression,style) |
Converts an expression from one data type to another data type |
The first parameter is the data type you want to convert to, the second parameter is the expression you want to convert, and the third parameter is the format style. Let’s look at some examples.
Using the CONVERT Function to Format Dates
Here are some examples of how to use the CONVERT function to format dates in SQL Server:
Example 1: Convert a datetime value to a string in the format of YYYY-MM-DD:
SELECT CONVERT(VARCHAR(10), GETDATE(), 120);
This will return a string in the format of YYYY-MM-DD.
Example 2: Convert a datetime value to a string in the format of MM/DD/YYYY:
SELECT CONVERT(VARCHAR(10), GETDATE(), 101);
This will return a string in the format of MM/DD/YYYY.
Example 3: Convert a datetime value to a string in the format of DD/MM/YYYY:
SELECT CONVERT(VARCHAR(10), GETDATE(), 103);
This will return a string in the format of DD/MM/YYYY.
As you can see, the third parameter of the CONVERT function specifies the format style we want to use. SQL Server provides many different styles to choose from.
Date Formats in SQL Server
SQL Server provides many different date formats that you can use to format dates. Here are just a few examples:
Style |
Description |
Example |
|---|---|---|
101 |
mm/dd/yyyy |
08/23/2022 |
102 |
yyyy.mm.dd |
2022.08.23 |
103 |
dd/mm/yyyy |
23/08/2022 |
104 |
dd.mm.yyyy |
23.08.2022 |
105 |
dd-mm-yyyy |
23-08-2022 |
106 |
dd mon yyyy |
23 Aug 2022 |
107 |
Mon dd, yyyy |
Aug 23, 2022 |
108 |
hh:mm:ss |
13:30:45 |
You can find the full list of supported styles in the SQL Server documentation.
Using the Format Function in SQL Server 2012 and Later Versions
If you are using SQL Server 2012 or later versions, you can also use the FORMAT function to format dates. The FORMAT function is similar to the CONVERT function, but it provides more flexibility in formatting dates. The syntax of the FORMAT function is as follows:
Function |
Description |
|---|---|
FORMAT (value, format [, culture ]) |
Formats a value with the specified format and an optional culture. |
The first parameter is the value you want to format, the second parameter is the format string, and the third parameter is the culture (optional). Let’s look at some examples.
Using the FORMAT Function to Format Dates
Here are some examples of how to use the FORMAT function to format dates in SQL Server:
Example 1: Format a datetime value to a string in the format of YYYY-MM-DD:
SELECT FORMAT(GETDATE(), 'yyyy-MM-dd');
This will return a string in the format of YYYY-MM-DD.
Example 2: Format a datetime value to a string in the format of MM/DD/YYYY:
SELECT FORMAT(GETDATE(), 'MM/dd/yyyy');
This will return a string in the format of MM/DD/YYYY.
Example 3: Format a datetime value to a string in the format of DD/MM/YYYY:
SELECT FORMAT(GETDATE(), 'dd/MM/yyyy');
This will return a string in the format of DD/MM/YYYY.
As you can see, the second parameter of the FORMAT function specifies the format string we want to use. SQL Server provides many different format strings to choose from.
Date Formatting Best Practices
Now that we’ve covered the basics of formatting dates in SQL Server, let’s talk about some best practices to keep in mind when working with dates.
Avoid Ambiguous Date Formats
When formatting dates in SQL Server, it’s essential to avoid ambiguous date formats that can cause confusion. For example, the date format ‘MM/DD/YYYY’ can be interpreted differently in different parts of the world. In some countries, it means the month comes first, followed by the day and year, while in others, it means the day comes first, followed by the month and year. Use unambiguous date formats like ‘YYYY-MM-DD’ or ‘DD/MM/YYYY’ instead.
Store Dates in UTC
When storing dates in SQL Server, it’s best practice to store them in UTC (Coordinated Universal Time) format. UTC is the standard time zone used in international data exchange and ensures that your dates are consistent across different time zones. When displaying dates to users, you can convert them to a local time zone as needed.
Use Consistent Date Formats
When working with dates in SQL Server, it’s important to use consistent date formats throughout your application. If you switch between different date formats, you risk confusing users and introducing errors in your code. Stick with a standardized date format and make sure to document it.
Date Formatting FAQ
Q: Can I use custom date formats in SQL Server?
A: Yes, you can use custom date formats in SQL Server by using the CONVERT or FORMAT functions with a custom format string. For example, you can use the format string ‘ddd MMM d, yyyy’ to format a date as ‘Thu Aug 23, 2022’.
Q: How can I convert a string to a date in SQL Server?
A: You can use the CONVERT or TRY_CONVERT function to convert a string to a date in SQL Server. For example:
SELECT CONVERT(DATE, '2022-08-23');
This will convert the string ‘2022-08-23’ to a date in SQL Server.
Q: How can I add or subtract days from a date in SQL Server?
A: You can use the DATEADD function to add or subtract days from a date in SQL Server. For example:
SELECT DATEADD(DAY, 7, '2022-08-23');
This will add 7 days to the date ‘2022-08-23’ and return the resulting date.
Q: How can I compare dates in SQL Server?
A: You can use the standard comparison operators (such as =, <, >, <=, >=) to compare dates in SQL Server. For example:
SELECT * FROM orders WHERE order_date > '2022-08-23';
This will return all orders with an order date greater than ‘2022-08-23’.
Conclusion
Formatting dates in SQL Server is an essential skill for any developer working with databases. In this comprehensive guide, we’ve covered everything you need to know to format dates in SQL Server, including the basics of how dates work in SQL Server, how to use the CONVERT and FORMAT functions, best practices for date formatting, and frequently asked questions. We hope you found this guide helpful and that you’ll be able to use these techniques to improve the clarity and consistency of your data.