Question

In SQL Server 2008 R2, I have to compare two dates of birth from different tables.

• column C.date_of_birth is of type DATETIME
• column R.dob is a date stored as VARCHAR, but with no leading zeroes on the month or day parts to make its length consistent (<–that’s the tough part).

I’ve gotten as close as this:

where R.dob <> convert(varchar, cast(C.date_of_birth as DATE), 101)

but that returns too many rows because 1/5/1923 in R.dob does not match 01/05/1923 in C.date_of_birth.

How can I format R.dob so it can correctly be compared to C.date_of_birth?

Thank you.

Answer 1

You can cast your varchar as a datetime. For instance, the result of this:

select cast('1/5/1923' as datetime)

Would be 1923-01-05 00:00:00.000

Then you can just use DATEDIFF() to compare them to see which are equal to the day (or whatever interval you so desire).