SQL Date Queries

Question

Please help me understand the SQL Select statement below:

Select DATEADD(DAY, DATEDIFF(DAY, 0, GETDATE()) - 1, 0)

The 0s are throwing me off.

Bond · Accepted Answer · 2015-08-01 01:03:55Z

5

The date 0 is interpreted as 1/1/1900.

This statement is determining the number of days since 1/1/1900:

DATEDIFF(DAY, 0, GETDATE())

It's wrapped in another call that adds that many days, minus 1, to 1/1/1990 (0).

DATEADD(DAY, <from above> - 1, 0)

Essentially giving you yesterday's date.

answered Aug 1, 2015 at 1:03

Bond

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1 Comment

More specifically, it will give you midnight yesterday. It strips the time from the datetime value which getdate() returns.