How do I query for all dates greater than a certain date in SQL Server?

Question

I am trying:

SELECT * 
FROM dbo.March2010 A
WHERE A.Date >= 2010-04-01;

 A.Date looks like: 2010-03-04 00:00:00.000

But, this is not working.

Can anybody give a reference for why?

Answer 1

select *  
from dbo.March2010 A 
where A.Date >= Convert(datetime, '2010-04-01' )

In this query, 2010-4-01 is treated as a mathematical expression. Therefore, in essence, it reads

select *  
from dbo.March2010 A 
where A.Date >= 2005; 

(2010 minus 4 minus 1 is 2005, converting this to a proper datetime and adding single quotes will solve this problem.)

So the parser here might allow you to get away with

select *  
from dbo.March2010 A 
where A.Date >= '2010-04-01'

It will be doing the conversion for you, but in my view, it is less readable than explicitly converting to a datetime for the maintenance programmer that will come after you. 

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