Greetings, fellow Devs! In this journal article, we will be discussing the conversion of dates to strings in SQL Server. This is a common task that developers encounter in various projects, and we aim to provide a comprehensive guide to help you through it. Throughout this article, we will provide step-by-step instructions, code snippets, and explanations in a relaxed and easy-to-understand manner. Let’s dive in!
What is Date to String Conversion?
Before we proceed, let us first understand what date to string conversion means. In SQL Server, dates are stored as numerical values, but they can be displayed in various formats using the CONVERT function. Converting a date to a string means converting the numerical value into a human-readable format that can be displayed on an application or web page.
Why Do We Need to Convert Dates to Strings?
There are various reasons why developers need to convert dates to strings. Some of these reasons include:
Reason |
Example |
|---|---|
Displaying dates in a specific format |
Displaying dates as “MM/DD/YYYY” instead of “YYYY-MM-DD” |
Sorting dates in a specific order |
Sorting dates as “YYYY-MM-DD” instead of “MM/DD/YYYY” |
Displaying dates in different languages |
Displaying dates as “DD/MM/YYYY” instead of “MM/DD/YYYY” for users in different regions |
Now that we’ve established the importance of date to string conversion, let’s proceed to the different methods we can use.
Method 1: Using the CONVERT Function
The CONVERT function is a built-in function in SQL Server that allows us to convert data types, including dates. We can use this function to convert dates to different string formats.
Step 1: Understanding the Syntax of the CONVERT Function
The syntax of the CONVERT function is as follows:
CONVERT(data_type,length,expression)
where:
- data_type: The data type to which the expression should be converted. In this case, we will be using the data type “varchar” to convert the date to a string.
- length: The length of the string that will be returned. This parameter is optional, but we will set it to a specific value in our examples.
- expression: The expression that will be converted to a string. In this case, we will use the date field that we want to convert.
Step 2: Converting a Date to a String
Let’s say we have a table called “orders” that has a column called “order_date” in “YYYY-MM-DD” format, and we want to display it as “MM/DD/YYYY” format. We can use the CONVERT function as follows:
SELECT CONVERT(varchar(10), order_date, 101) AS order_date_formatted FROM orders
Explanation:
varchar(10)– We’re converting the date to a string with a length of 10 characters.order_date– The date column that we want to convert.101– The style parameter that specifies the format of the converted string. In this case, we’re using “101” to represent “MM/DD/YYYY” format.AS order_date_formatted– We’re giving the converted string a column alias of “order_date_formatted”.
Executing this query will return a result set with the “order_date_formatted” column displaying the date in “MM/DD/YYYY” format.
Step 3: Converting a Date and Time to a String
If we have a date column that also includes a time component, we can use a different style parameter to convert it to a string. For example, let’s say we have a table called “orders” that has a column called “order_date_time” in “YYYY-MM-DD HH:MI:SS” format, and we want to display it as “MM/DD/YYYY HH:MI AM (or PM)” format. We can use the CONVERT function as follows:
SELECT CONVERT(varchar(30), order_date_time, 100) + ' ' + RIGHT(CONVERT(varchar(30), order_date_time, 109), 2) AS order_date_time_formatted FROM orders
Explanation:
varchar(30)– We’re converting the datetime to a string with a length of 30 characters.order_date_time– The datetime column that we want to convert.100– The style parameter that specifies the format of the converted string. In this case, we’re using “100” to represent “YYYY-MM-DD HH:MI:SS” format.RIGHT(CONVERT(varchar(30), order_date_time, 109), 2)– This converts the time component of the datetime to “HH:MI AM (or PM)” format.+ ' '– This concatenates the date and time strings.AS order_date_time_formatted– We’re giving the converted string a column alias of “order_date_time_formatted”.
Executing this query will return a result set with the “order_date_time_formatted” column displaying the datetime in “MM/DD/YYYY HH:MI AM (or PM)” format.
Method 2: Using the FORMAT Function (SQL Server 2012 and Later)
The FORMAT function is another built-in function in SQL Server that allows us to format data types, including dates. We can use this function to easily convert dates to different string formats without having to remember style parameters.
Step 1: Understanding the Syntax of the FORMAT Function
The syntax of the FORMAT function is as follows:
FORMAT(expression, format)
where:
- expression: The expression that will be formatted. In this case, we will use the date field that we want to convert.
- format: The format string that will be used to format the expression. This parameter is required and can include placeholders for date and time values. We will explore the different placeholders in the examples below.
Step 2: Converting a Date to a String
Let’s say we have a table called “orders” that has a column called “order_date” in “YYYY-MM-DD” format, and we want to display it as “MM/DD/YYYY” format. We can use the FORMAT function as follows:
SELECT FORMAT(order_date, 'MM/dd/yyyy') AS order_date_formatted FROM orders
Explanation:
order_date– The date column that we want to convert.'MM/dd/yyyy'– The format string that we want to use to display the date. The placeholders “MM”, “dd”, and “yyyy” represent the month, day, and year components of the date, respectively.AS order_date_formatted– We’re giving the formatted string a column alias of “order_date_formatted”.
Executing this query will return a result set with the “order_date_formatted” column displaying the date in “MM/DD/YYYY” format.
Step 3: Converting a Date and Time to a String
If we have a date column that also includes a time component, we can use a different format string to convert it to a string. For example, let’s say we have a table called “orders” that has a column called “order_date_time” in “YYYY-MM-DD HH:MI:SS” format, and we want to display it as “MM/DD/YYYY hh:mi AM (or PM)” format. We can use the FORMAT function as follows:
SELECT FORMAT(order_date_time, 'MM/dd/yyyy hh:mm tt') AS order_date_time_formatted FROM orders
Explanation:
order_date_time– The datetime column that we want to convert.'MM/dd/yyyy hh:mm tt'– The format string that we want to use to display the datetime. The placeholders “MM”, “dd”, “yyyy”, “hh”, “mm”, and “tt” represent the month, day, year, hour (in 12-hour format), minute, and AM/PM indicator components of the datetime, respectively.AS order_date_time_formatted– We’re giving the formatted string a column alias of “order_date_time_formatted”.
Executing this query will return a result set with the “order_date_time_formatted” column displaying the datetime in “MM/DD/YYYY hh:mi AM (or PM)” format.
FAQs
What are the different style parameters that can be used in CONVERT?
Here are some of the commonly used style parameters for converting dates to strings:
Style Parameter |
Description |
Example |
|---|---|---|
101 |
MM/DD/YYYY |
CONVERT(varchar(10), order_date, 101) |
102 |
YYYY.MM.DD |
CONVERT(varchar(10), order_date, 102) |
103 |
DD/MM/YYYY |
CONVERT(varchar(10), order_date, 103) |
110 |
MM-DD-YYYY |
CONVERT(varchar(10), order_date, 110) |
120 |
YYYY-MM-DD HH:MI:SS |
CONVERT(varchar(19), order_date_time, 120) |
126 |
YYYY-MM-DDTHH:MI:SS.mmm |
CONVERT(varchar(23), order_date_time, 126) |
Can I use custom format strings in FORMAT?
Yes, you can use custom format strings in FORMAT. Here are some examples:
Custom Format String |
Description |
Example |
|---|---|---|
MM/DD/YY |
Month/day/year in 2-digit format |
FORMAT(order_date, ‘MM/dd/yy’) |
MMMM dd, yyyy |
Month name, day, year |
FORMAT(order_date, ‘MMMM dd, yyyy’) |
hh:mm:ss tt |
12-hour format time with AM/PM indicator |
FORMAT(order_date_time, ‘hh:mm:ss tt’) |
Is there a difference between using CONVERT and FORMAT?
Yes, there are some differences between using CONVERT and FORMAT:
- CONVERT requires a style parameter to specify the format of the output, while FORMAT requires a format string.
- CONVERT is more flexible in terms of converting dates to different formats, but requires knowledge of the style parameters. FORMAT is easier to use for common date formats, but may not support all possible formats.
- CONVERT can be used in earlier versions of SQL Server, while FORMAT is only available in SQL Server 2012 and later.
Conclusion
We have reached the end of our comprehensive guide for date to string conversion in SQL Server. We hope that this article has provided you with valuable insights and practical examples that you can use in your future projects. Always remember that proper formatting and conversion of data types can greatly improve the usability and readability of your applications. Happy coding, Devs!