How to Correctly Query for Dates Greater Than a Specific Date in SQL Server?

Querying for Dates Greater Than a Specific Date in SQL Server

In an attempt to retrieve records with dates later than a specified date, you may encounter issues with your query. For example, a query similar to the one below:

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

where A.Date is in the format 2010-03-04 00:00:00.000, may not yield the expected results.

To resolve this issue, it is crucial to convert the date expression to the proper datetime format using the Convert function. The correct syntax is:

SELECT *  
FROM dbo.March2010 A 
WHERE A.Date >= Convert(datetime, '2010-04-01' )

The reason for this is that when using mathematical expressions, SQL Server treats the date value as a number, resulting in incorrect comparisons. Converting the date to datetime ensures that the comparison is made correctly.

While SQL Server may allow for implicit conversion using single quotes, such as:

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

it is considered less readable and less reliable than the explicit conversion method. Explicit conversion ensures the proper handling of dates, regardless of the user settings or current system date.

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