Welcome, Dev, to this tutorial on how to convert date to string in SQL Server. In this article, we will cover everything you need to know about converting a date to a string format in SQL Server, including the different functions you can use, how to format the output, and some common questions and answers. So, let’s get started!
Part 1: Introduction to Date and Time in SQL Server
Before we dive into converting dates to strings, let’s first understand the basics of date and time in SQL Server. In SQL Server, dates are stored as datetime or smalldatetime data types, which store both the date and time information. The datetime data type stores the date and time with an accuracy of up to 3.33 milliseconds, while the smalldatetime data type stores the date and time with an accuracy of up to one minute.
To retrieve the current date and time in SQL Server, you can use the GETDATE() function. For example:
SQL Query |
Result |
|---|---|
SELECT GETDATE() |
2021-09-06 08:37:23.940 |
Now that we have a basic understanding of date and time in SQL Server, let’s move on to converting dates to strings.
Part 2: Converting Dates to Strings
1. CAST and CONVERT Functions
The easiest way to convert a date to a string in SQL Server is to use the CAST or CONVERT function. The CAST function converts an expression of one data type to another data type, while the CONVERT function converts an expression of one data type to another data type with a specified style.
The syntax for using the CAST function to convert a date to a string is:
CAST (expression AS data_type)
For example, to convert the current date and time to a string in the format of ‘yyyy-mm-dd hh:mm:ss’, you can use the following query:
SQL Query |
Result |
|---|---|
SELECT CAST(GETDATE() AS VARCHAR(19)) |
2021-09-06 08:37:23 |
The syntax for using the CONVERT function to convert a date to a string is:
CONVERT (data_type, expression [, style ])
For example, to convert the current date and time to a string in the format of ‘dd/mm/yyyy’, you can use the following query:
SQL Query |
Result |
|---|---|
SELECT CONVERT(VARCHAR(10), GETDATE(), 103) |
06/09/2021 |
Note that the ‘style’ parameter in the CONVERT function specifies the output format of the date string. You can find a full list of styles on the Microsoft Docs website.
2. FORMAT Function
The FORMAT function is another way to convert a date to a string in SQL Server. This function allows you to specify the output format using .NET format strings.
The syntax for using the FORMAT function to convert a date to a string is:
FORMAT (value, format [, culture ])
For example, to convert the current date and time to a string in the format of ‘yyyy/MM/dd’, you can use the following query:
SQL Query |
Result |
|---|---|
SELECT FORMAT(GETDATE(), ‘yyyy/MM/dd’) |
2021/09/06 |
Note that the ‘culture’ parameter in the FORMAT function specifies the culture-specific formatting to use. If you omit this parameter, SQL Server uses the current session’s language setting.
Part 3: Formatting Date Strings
Now that we know how to convert dates to strings in SQL Server, let’s look at some common ways to format the output.
1. Adding Timezone to Date String
If you need to add the timezone information to the date string, you can use the T-SQL statement below:
SELECT CONVERT(VARCHAR(19), SWITCHOFFSET(CONVERT(DATETIMEOFFSET, GETDATE()), DATENAME(TZOFFSET, SYSDATETIMEOFFSET())), 120)The result of the query is:
| Result |
|---|
| 2021-09-06 08:37:23 |
Notice that in the above example, we are using the SWITCHOFFSET function which converts the current date and time to the specified timezone, and the DATENAME function which retrieves the name of the timezone offset of the current timezone.
2. Converting Dates to Short Month Names
If you need to convert a date to the short name of the month (e.g. ‘Jan’, ‘Feb’, ‘Mar’), you can use the following query:
SELECT REPLACE(CONVERT(VARCHAR(11), GETDATE(), 106), ' ', '-')The result of the query is:
| Result |
|---|
| 06-Sep-2021 |
Notice that in the above example, we are using the REPLACE function to replace the space between the day and the month name with a hyphen (-).
Part 4: Frequently Asked Questions
1. Can I convert a string to a date in SQL Server?
Yes, you can use the CAST or CONVERT function to convert a string to a date in SQL Server. For example:
SELECT CAST('20210906' AS DATE)The result of the query is:
| Result |
|---|
| 2021-09-06 |
2. Can I convert a datetime to a UNIX timestamp in SQL Server?
Yes, you can use the DATEDIFF function to calculate the difference between the datetime value and ‘1970-01-01 00:00:00.000’ (the UNIX epoch) in seconds. For example:
SELECT DATEDIFF(SECOND, '1970-01-01 00:00:00.000', GETDATE())The result of the query is:
| Result |
|---|
| 1630911443 |
Notice that in the above example, we are using the SECOND parameter in the DATEDIFF function to calculate the difference in seconds.
3. Can I convert a date to a string with a custom format?
Yes, you can use the CONVERT or FORMAT function to convert a date to a string with a custom format. For example:
SELECT CONVERT(VARCHAR(10), GETDATE(), 111) + ' ' + CONVERT(VARCHAR(8), GETDATE(), 108)The result of the query is:
| Result |
|---|
| 2021/09/06 08:37:23 |
Notice that in the above example, we are using the ‘+’ operator to concatenate the output of two CONVERT functions – one for the date part and one for the time part.
4. Can I apply formatting to a datetime value before inserting it into a database?
Yes, you can format a datetime value before inserting it into a database using the CONVERT or FORMAT function. For example:
INSERT INTO [Table] ([DateColumn]) VALUES (CONVERT(DATETIME, '2021/09/06', 111))Notice that in the above example, we are using the CONVERT function to convert the string ‘2021/09/06’ to a datetime value before inserting it into the [DateColumn] column of the [Table] table.
5. How do I convert a date to a string in a stored procedure?
To convert a date to a string in a stored procedure, you can use the same functions and syntax as we have discussed in this article. For example:
CREATE PROCEDURE [dbo].[GetDateAsString]ASBEGINSELECT CONVERT(VARCHAR(19), GETDATE(), 120) AS 'Date'ENDEXEC [dbo].[GetDateAsString]Notice that in the above example, we are creating a stored procedure that returns the current date and time as a string in the format of ‘yyyy-mm-dd hh:mm:ss’, using the CONVERT function.
Conclusion
In this tutorial, we have covered everything you need to know about converting a date to a string in SQL Server. We have looked at the different functions and syntax you can use, how to format the output, and some common questions and answers. Hopefully, this tutorial has been helpful for you, and you are now able to convert dates to strings in SQL Server with confidence.