Question

I have a datetime field in my table. I want to delete records based on a date but I am not interested in the time element. How would I write the SQL for this ? I am using MS SQL 2008.

Answer 1

For best use of indexes, I’d go for this kind of approach:

To delete all records for 1st December:

DECLARE @DateToDelete DATETIME
SET @DateToDelete = '20091201' 

DELETE FROM MyTable
WHERE MyDateField >= @DateToDelete AND MyDateField < DATEADD(dd, 1, @DateToDelete)

The alternatives include:

DELETE FROM MyTable
WHERE CAST(CONVERT(VARCHAR(10), MyDateField, 120) AS DATETIME) = @DateToDelete

which converts each datetime value to just it’s date part.

But I’d still go with my original way as it allows for more efficient execution.