Understanding SQL Server Convert Date

Hello Dev, we’re glad to have you with us today to explore the topic of “SQL Server Convert Date.” As you may know, dates are a critical part of any database, and it’s essential to understand how they function in the SQL Server. In this article, we’ll be walking you through everything you need to know about converting dates in the SQL Server, from basic concepts to advanced techniques.

What is a Date in SQL Server?

Before we dive into how to convert dates, let’s first define what a date is in SQL Server. A date is a data type that represents a specific point in time in a specific time zone. It contains both the date and the time, with precision down to milliseconds. The format of the date can vary depending on the settings of the specific SQL Server instance.

SQL Server also supports other date-related data types, such as datetime2, datetimeoffset, and smalldatetime, but for the purposes of this article, we’ll focus on the standard date data type.

Date Formats in SQL Server

When working with dates in SQL Server, it’s essential to be familiar with the different date formats that can be used. SQL Server supports four date formats:

Format	Description
mm/dd/yyyy	US standard
yyyy-mm-dd	ISO standard
dd mon yyyy	UK standard
mon dd, yyyy	Other standard

These different formats can be used when converting dates, and we’ll discuss them in more detail later on in this article.

Converting Dates in SQL Server

Using the CONVERT Function

One of the primary ways to convert dates in SQL Server is by using the CONVERT function. The CONVERT function allows you to convert a date from one data type to another. You can also use it to format the date in a specific way. Here’s an example:

SELECT CONVERT(varchar, getdate(), 101)

The above query will return the current date in the mm/dd/yyyy format, which is the US standard. In this case, we’re using the VARCHAR data type to store the date as a string.

Let’s break down the syntax of the CONVERT function:

Parameter	Description
data_type	The data type to which you want to convert the date.
expression	The date you want to convert.
style	The style in which you want to display the date.

There are several different styles that you can use in the CONVERT function, each of which corresponds to a different date format. Let’s take a look at some of the most common styles:

Style	Description
101	mm/dd/yyyy
102	yyyy.mm.dd
103	dd/mm/yyyy
104	dd.mm.yyyy
105	dd-mm-yyyy

By specifying the style parameter in the CONVERT function, you can convert the date to the format you need. The resulting value will be a string that represents the date in the specified format.

Using the CAST Function

Another way to convert dates in SQL Server is by using the CAST function. The CAST function allows you to convert values from one data type to another. Here’s an example:

SELECT CAST('2021-08-01' AS datetime)

The above query will convert the string ‘2021-08-01’ to a datetime value. The resulting value will be a datetime value that represents August 1st, 2021 at midnight.

When using the CAST function to convert dates, it’s important to ensure that the input value is in the correct format. Otherwise, the conversion may fail.

Formatting Dates in SQL Server

Using the FORMAT Function

In addition to converting dates, you may also need to format them in a specific way. SQL Server provides the FORMAT function, which allows you to format dates and times in a variety of ways. Here’s an example:

SELECT FORMAT(getdate(), 'MM/dd/yyyy')

The above query will return the current date in the mm/dd/yyyy format.

The FORMAT function takes two parameters:

Parameter	Description
expression	The date or time you want to format.
format	The format in which you want to display the date or time.

There are many different format strings that you can use with the FORMAT function to display the date or time in the way you need.

FAQ

What date formats does SQL Server support?

SQL Server supports four date formats: mm/dd/yyyy, yyyy-mm-dd, dd mon yyyy, and mon dd, yyyy.

What is the difference between the CONVERT and CAST functions?

The CONVERT function is used to convert data from one data type to another, while the CAST function is used to convert data from one data type to another.

Can I format a date using the CONVERT function?

Yes, you can format a date using the CONVERT function by specifying the style parameter.

What is the FORMAT function used for?

The FORMAT function is used to format dates and times in a variety of ways.