Question

Here’s one more or less for perfection’s sake.

Microsoft SQL Server only contains the field type datetime for storing dates and times.

But let’s say that I want to store a list of business hours, where the date is completely irrelevant. Currently I’m using the datetime type and then simply displaying the time-portion of the data. But I have two problems with this.

1. It seems awkwardly inefficient.
2. It may confuse future developers to see a full-blown date coming along with the time, which they may not know whether is used anywhere or not.

And so it begs the question; in the absence of a specific time field (like in MySQL), what is the most optimal way of storing only a particular time of day, from 00:00 to 23:59?

UPDATE: It’s SQL Server 2005. (Also I’d just be interested in knowing what to do in general when there is no time type.)

Answer 1

For SQL Server 2005 or older…

If you only want to know to the minute, you can store it as an int in the range of 1-1440. 1 is 00:01 and 1440 is 0:00.

It would be easy do display as a time again if you like:

SELECT CAST((605 / 60) as varchar) + ':' + RIGHT('0' + CAST((605 % 60) as varchar), 2)

An additional advantage of this is that if you use a smallint data type you are saving 1-3 bytes per record from the built-in TIME datatype.

TIME uses 3-5 bytes per row and smallint is 2 bytes per row.

The extra bytes are for seconds and fractional seconds I believe.

EDIT

It’s more complicated with seconds but still doable I should think…

1-86400 range (seconds per day)

DECLARE @i INT
SET @i = 3661

SELECT RIGHT('0' + CAST((@i / 3600) as varchar),2) --hours
+ ':' + RIGHT('0' + CAST((@i % 3600)/60 as varchar), 2) -- minutes
+ ':' + RIGHT('0' + CAST((@i % 3600)%60 as varchar), 2) -- seconds