In my first article in this series, I discussed different aspects of entering date/time data into SQL Server DATETIME and SMALLDATE columns. This article will expand my discussion of date/time data by exploring how to use different SQL Server functions to display dates and times in different formats.

Depending on your environment, your needs, and/or the audience of your application, the format for displaying date and time might vary. Internationally we have many difference ways to represent a given date and/or time. Here are a few examples of different ways we might display the date January 22, 2003 with or without a time of 10:31 PM.

• 2003/01/22 10:31PM
• 2003/01/22 22:31
• 22-01-2003
• 22 January 2003
• Jan 22 2003 10:13PM
• January 22, 2003

Let's review the SQL Server functions that can be used to display these date formats, starting with the CONVERT function. The CONVERT function is provided to help with converting a DATETIME or SMALLDATETIME variables, or any other string that holds a valid date, into different date/time display formats. The CONVERT function is called using the following syntax:

	CONVERT ( data_type [ ( length) ] , expression [ , style ] )  

Where data_type [(length)] is the target data type format and length, expression is any valid Microsoft expression that represents the date/time you want to display, and style specifies the output format for the data/time.

Using the CONVERT function, with different styles, allows you to display date and time data in many different formats. Let's look at what I am taking about. The easiest way to demonstrate how to use the CONVERT function is to review some TSQL code that displays the current time in a few different display formats. The following script uses only the CONVERT function to display the different formats.

PRINT '1) HERE IS MON DD YYYY HH:MIAM (OR PM) FORMAT ==>' + 

CONVERT(CHAR(19),GETDATE())  

PRINT '2) HERE IS MM-DD-YY FORMAT ==>' + 

CONVERT(CHAR(8),GETDATE(),10)  

PRINT '3) HERE IS MM-DD-YYYY FORMAT ==>' + 

CONVERT(CHAR(10),GETDATE(),110) 

PRINT '4) HERE IS DD MON YYYY FORMAT ==>' + 

CONVERT(CHAR(11),GETDATE(),106)

PRINT '5) HERE IS DD MON YY FORMAT ==>' + 

CONVERT(CHAR(9),GETDATE(),6) 

PRINT '6) HERE IS DD MON YYYY HH:MM:SS:MMM(24H) FORMAT ==>' + 

CONVERT(CHAR(24),GETDATE(),113)

Here is the output from the above script:

1) HERE IS MON DD YYYY HH:MIAM (OR PM) FORMAT ==>Feb  5 2003  5:54AM

2) HERE IS MM-DD-YY FORMAT ==>02-05-03

3) HERE IS MM-DD-YYYY FORMAT ==>02-05-2003

4) HERE IS DD MON YYYY FORMAT ==>05 Feb 2003

5) HERE IS DD MON YY FORMAT ==>05 Feb 03

6) HERE IS DD MON YYYY HH:MM:SS:MMM(24H) FORMAT ==>05 Feb 2003 05:54:39:567

As you can see, this script displays the current date in many different formats. Some formats have two digit years, while others have four digit years. Some displays have 24 hour or AM/PM time formats. Still others have the month displayed as a numeric value, while others have a month abbreviation. Some of the displays also have the date displayed in DD MON YYYY format. I suggest you review Books Online for a description of all the formats that the CONVERT function can display using different styles.

Even though the CONVERT function has a number of data/time output styles, it still might not have the exact display format you need to display. Sometimes you will need to use other TSQL functions as well, to get the display format you desire.

Another important date/time function worth describing is DATEPART. This function will take a date/time expression and return a single part of the date, such as hour, minute, month, day, etc. A call to this function has the following form:

	DATEPART(datepart, date)>

Where the datepart is one of the following: Year, yy, yyyy, quarter, qq, q, month, mm, m, dayofyear, dy, y, day, dd, d, week, wk, ww, weekday, dw,hour, hh, minute, mi, n, second, ss, s, millisecond, or ms. And date is a valid date expression. This function will return an integer representing the particular date part requested.

Let's review how the CONVERT and/or DATEPART functions can be used to display January 22, 2003 with a time of 10:31 PM to meet all of the display formats I showed at the top of this article.

Some of the formats can be created using the different "style" options on the CONVERT statement. Although a number of these formats above will not only require the CONVERT and/or DATEPART functions, but other TSQL functions like SUBSTRING, RIGHT, and CAST to build the desired display format. If you are unfamiliar with these additional functions, read Books Online for more information. To show you how to create each of these display formats I will build a simple script for each of the different formats.