CAST(DATETIME AS DATE) over WHERE clause

Question

I\'m using SQL Server 2012 and I would like to know if I write the sentence:

SELECT MyDateTimeColumn 
FROM MyTable
WHERE CAST(MyDateTimeColumn AS DATE) = \'         


        

Answer 1

Use this proven method to "zero out" the time component of a datetime:

select MyDateTimeColumn
from MyTable
where DATEADD(dd, DATEDIFF(dd, 0, MyDateTimeColumn), 0) = CONVERT(date, '07-09-2014', 110)

Avoid casting to different date types if there's a faster way (like the trick above), and definitely try to avoid using string literals for dates without wrapping them in a CONVERT() to ensure your string format will get interpreted correctly.

If you have performance concerns and want to force it to use an index, I would suggest adding a column that is of type date (fill it with the existing column's value minus the time part), and index/search on that, or create an indexed view that accomplishes the same thing.