SQL Server: How to select rows that were inserted on the same day?

Question

I have a loop, that goes through some entries. In the loop I'm getting creation date and I need to find if there were entries inserted on the same day. So for example if creation date = 2011-08-31 21:19:14.345, I need to select all rows where the creation date is between 2011-08-31 00:00:00.000 and 2011-08-31 23:59:59.999

How do I do this with SQL?

Answer 1

Without any other schema details, and if this is SQL Server 2K8+, you could do this:

DECLARE @CreationDate Date = '2011-08-31';

SELECT *
FROM SomeTable
WHERE CONVERT(Date, CreationDate) = @CreationDate;

By converting to a date instead of working with datetime you lose the time component and "normalize" how you're comparing the values.

Another way to lose the time component for comparison purposes is:

DECLARE @CreationDate DateTime;
SELECT @CreationDate = '2011-08-31 21:19:14.345';

SELECT @CreationDate; -- 2011-08-31 21:19:14.345
SELECT @CreationDate = CONVERT(DateTime, FLOOR(CONVERT(Float, @CreationDate)));
SELECT @CreationDate; -- 2011-08-31 00:00:00.000

You would use that if you don't have the date data type.

Answer 2

In order to catch all the times in that day do this:

SELECT * FROM MyTable
WHERE DateCreated >= @TheDate AND DateCreated < DATEADD(day, 1, @TheDate)

Where @TheDate must be the pure date without time. It works even when DateCreated has a time part very close to midnight.

Answer 3

You can try this:

SELECT * FROM SomeTable  
WHERE   
DAY(TDATE) = DAY(CreationDate)  
AND  
MONTH(TDATE) = MONTH(CreationDate)  
AND  
YEAR(TDATE) = YEAR(CreationDate)