Best way to compare dates without time in SQL Server

Question

select * from sampleTable 
where CONVERT(VARCHAR(20),DateCreated,101) 
=     CONVERT(VARCHAR(20),CAST(\'Feb 15 2012  7:00:00:000PM\' AS DATETIME),101)

Answer 1

Description

Don't convert your Date to a varchar and compare because string comparisson is not fast.

It is much faster if you use >= and < to filter your DateCreated column.

If you have no parameter (like in your sample, a string) you should use the ISO Format <Year><Month><Day>.

Sample

According to your sample

DECLARE @startDate DateTime
DECLARE @endDate DateTime

SET @startDate = '20120215'
SET @endDate = DATEADD(d,1,@startDate)

SELECT * FROM sampleTable 
WHERE DateCreated >= @startDate AND DateCreated < @endDate

More Information

• MSDN - DATEADD (Transact-SQL)

Answer 2

Don't use convert - that involves strings for no reason. A trick is that a datetime is actually a numeric, and the days is the integer part (time is the decimal fraction); hence the day is the FLOOR of the value: this is then just math, not strings - much faster

declare @when datetime = GETUTCDATE()
select @when -- date + time
declare @day datetime = CAST(FLOOR(CAST(@when as float)) as datetime)
select @day -- date only

In your case, no need to convert back to datetime; and using a range allows the most efficent comparisons (especially if indexed):

declare @when datetime = 'Feb 15 2012  7:00:00:000PM'
declare @min datetime = FLOOR(CAST(@when as float))
declare @max datetime = DATEADD(day, 1, @min)

select * from sampleTable where DateCreated >= @min and DateCreated < @max

Answer 3

Simple Cast to Date will resolve the problem.

DECLARE @Date datetime = '04/01/2016 12:01:31'

DECLARE @Date2 datetime = '04/01/2016'

SELECT CAST(@Date as date)

SELECT CASE When (CAST(@Date as date) = CAST(@Date2 as date)) Then 1 Else 0 End

Answer 4

declare @DateToday Date= '2019-10-1'; print @DateToday;

print Abs(datediff(day, @DateToday,CAST('oct 1 2019 7:00:00:000PM' AS DATETIME))) < 3

this is compare whin 3 days.

i test this on SQL Server 2014, it works.

Answer 5

SELECT .......
FROM ........
WHERE 
CAST(@DATETIMEVALUE1 as DATE) = CAST(@DATETIMEVALUE2 as DATE)

The disadvantage is that you are casting the filter column.

If there is an index on the filter column, then, since you are casting, the SQL engine can no longer use indexes to filter the date more efficiently.

Answer 6

Use 112 CONVERT's format

select * 
from sampleTable 
where 
  CONVERT(VARCHAR(20),DateCreated,112) 
=     CONVERT(VARCHAR(20),CAST('Feb 15 2012  7:00:00:000PM' AS DATETIME),112)

or

if your sql server version 2008+ use DATE type

select * from sampleTable 
where CONVERT(DATE,DateCreated) 
=     CONVERT(DATE,CAST('Feb 15 2012  7:00:00:000PM' AS DATETIME))