Select the last 48 hours dynamically

Question

I have a table with 2 dates.

Date A
Date B

I need to select all the rows where date B happened WITHIN 48 hours after date A.

Sample Data

Date A          Date B
1/28/2011   1/19/2014
12/21/2010  1/18/2014
2/5/2014    2/7/2014

In this case the 3rd row qualifies

Answer 1

DATEADD() should do the trick. SELECT DATEADD(hh, 48, getdate()) returns 48 hours from now.

In your example you could replace getdate() with Date A, somewhere along the lines of:

SELECT DateB
FROM   x
WHERE  DateB BETWEEN DateA AND DATEADD(hh, 48, DateA)

Answer 2

SELECT DateA, DateB
FROM dbo.TableName
WHERE DATEDIFF(hour, DateA, DateB) <= 48

Sql-Fiddle

Use ABS if it's not important which date is earlier.