Can I make SQL Server format dates and times for me?

Many people have asked if there is a way to make SQL Server behave the way FORMAT works in VB (and FormatDateTime in VBScript). What they'd like to see is the ability to tell SQL Server to format a date with long date and time, or in MM/DD/YYYY format, instead of having to memorize existing format conversion numbers and/or manipulate the strings themselves. For example, to get today's date in YYYYMMDD format, you currently need to call the following:

SELECT CONVERT(CHAR(8), GETDATE(), 112)

What does the 112 mean? Nothing. It's just an arbitrary number representing this specific format (Kalen Delaney's Inside SQL Server 2000 has a detailed explanation of the more commonly-used conversions).

Now, wouldn't it be nice to be able to say this:

SELECT CONVERT(VARCHAR, GETDATE(), 'YYYYMMDD')

?

Well, now you can, if you're using SQL Server 2000. I designed this scalar user-defined function for specifically this purpose.

CREATE FUNCTION dbo.FormatDateTime
(
@dt DATETIME,
@format VARCHAR(16)
)
RETURNS VARCHAR(64)
AS
BEGIN
DECLARE @dtVC VARCHAR(64)
SELECT @dtVC = CASE @format

WHEN 'LONGDATE' THEN

DATENAME(dw, @dt)
+ ',' + SPACE(1) + DATENAME(m, @dt)
+ SPACE(1) + CAST(DAY(@dt) AS VARCHAR(2))
+ ',' + SPACE(1) + CAST(YEAR(@dt) AS CHAR(4))

WHEN 'LONGDATEANDTIME' THEN

DATENAME(dw, @dt)
+ ',' + SPACE(1) + DATENAME(m, @dt)
+ SPACE(1) + CAST(DAY(@dt) AS VARCHAR(2))
+ ',' + SPACE(1) + CAST(YEAR(@dt) AS CHAR(4))
+ SPACE(1) + RIGHT(CONVERT(CHAR(20),
@dt - CONVERT(DATETIME, CONVERT(CHAR(8),
@dt, 112)), 22), 11)

WHEN 'SHORTDATE' THEN

LEFT(CONVERT(CHAR(19), @dt, 0), 11)

WHEN 'SHORTDATEANDTIME' THEN

REPLACE(REPLACE(CONVERT(CHAR(19), @dt, 0),
'AM', ' AM'), 'PM', ' PM')

WHEN 'UNIXTIMESTAMP' THEN

CAST(DATEDIFF(SECOND, '19700101', @dt)
AS VARCHAR(64))

WHEN 'YYYYMMDD' THEN

CONVERT(CHAR(8), @dt, 112)

WHEN 'YYYY-MM-DD' THEN

CONVERT(CHAR(10), @dt, 23)

WHEN 'YYMMDD' THEN

CONVERT(VARCHAR(8), @dt, 12)

WHEN 'YY-MM-DD' THEN

STUFF(STUFF(CONVERT(VARCHAR(8), @dt, 12),
5, 0, '-'), 3, 0, '-')

WHEN 'MMDDYY' THEN

REPLACE(CONVERT(CHAR(8), @dt, 10), '-', SPACE(0))

WHEN 'MM-DD-YY' THEN

CONVERT(CHAR(8), @dt, 10)

WHEN 'MM/DD/YY' THEN

CONVERT(CHAR(8), @dt, 1)

WHEN 'MM/DD/YYYY' THEN

CONVERT(CHAR(10), @dt, 101)

WHEN 'DDMMYY' THEN

REPLACE(CONVERT(CHAR(8), @dt, 3), '/', SPACE(0))

WHEN 'DD-MM-YY' THEN

REPLACE(CONVERT(CHAR(8), @dt, 3), '/', '-')

WHEN 'DD/MM/YY' THEN

CONVERT(CHAR(8), @dt, 3)

WHEN 'DD/MM/YYYY' THEN

CONVERT(CHAR(10), @dt, 103)

WHEN 'HH:MM:SS 24' THEN

CONVERT(CHAR(8), @dt, 8)

WHEN 'HH:MM 24' THEN

LEFT(CONVERT(VARCHAR(8), @dt, 8), 5)

WHEN 'HH:MM:SS 12' THEN

LTRIM(RIGHT(CONVERT(VARCHAR(20), @dt, 22), 11))

WHEN 'HH:MM 12' THEN

LTRIM(SUBSTRING(CONVERT(
VARCHAR(20), @dt, 22), 10, 5)
+ RIGHT(CONVERT(VARCHAR(20), @dt, 22), 3))

ELSE

'Invalid format specified'

END
RETURN @dtVC
END
GO

(If you're using SQL Server 7.0, you can't create UDFs; so, I suppose you could put this logic into a stored procedure, and put the result into an output parameter.)

Sample usage:

DECLARE @now DATETIME
SET @now = GETDATE()

PRINT dbo.FormatDateTime(@now, 'LONGDATE')
PRINT dbo.FormatDateTime(@now, 'LONGDATEANDTIME')
PRINT dbo.FormatDateTime(@now, 'SHORTDATE')
PRINT dbo.FormatDateTime(@now, 'SHORTDATEANDTIME')
PRINT dbo.FormatDateTime(@now, 'UNIXTIMESTAMP')
PRINT dbo.FormatDateTime(@now, 'YYYYMMDD')
PRINT dbo.FormatDateTime(@now, 'YYYY-MM-DD')
PRINT dbo.FormatDateTime(@now, 'YYMMDD')
PRINT dbo.FormatDateTime(@now, 'YY-MM-DD')
PRINT dbo.FormatDateTime(@now, 'MMDDYY')
PRINT dbo.FormatDateTime(@now, 'MM-DD-YY')
PRINT dbo.FormatDateTime(@now, 'MM/DD/YY')
PRINT dbo.FormatDateTime(@now, 'MM/DD/YYYY')
PRINT dbo.FormatDateTime(@now, 'DDMMYY')
PRINT dbo.FormatDateTime(@now, 'DD-MM-YY')
PRINT dbo.FormatDateTime(@now, 'DD/MM/YY')
PRINT dbo.FormatDateTime(@now, 'DD/MM/YYYY')
PRINT dbo.FormatDateTime(@now, 'HH:MM:SS 24')
PRINT dbo.FormatDateTime(@now, 'HH:MM 24')
PRINT dbo.FormatDateTime(@now, 'HH:MM:SS 12')
PRINT dbo.FormatDateTime(@now, 'HH:MM 12')
PRINT dbo.FormatDateTime(@now, 'goofy')