How to create fast database queries

Archive for August 21st, 2009

SQL Server: finding date closest to a birthdate

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From Stack Overflow:

The problem is with dynamically getting upcoming what we call namedays in Europe.

Name day is a tradition in many countries in Europe and Latin America of celebrating on a particular day of the year associated with the one's given name.

Here's a sampe name day table (I store the date in this format: 1900-08-22, but we really only need month and day):

First name Name day
Bob 1900-04-22
Bob 1900-09-04
Frank 1900-01-02

The trick is that there might be multiple name days for each name, and someones name day is always the first one found after ones birthday.

So if Bob was born on August 5th, his name day would fall on September 4th, but if we were born after Sep 4th, his name day would be on April 22nd.

We need to find when a given person celebrates his/her name day based on the first name and birthdate.

What I need is an SQL Server query that will be able to get me name days for the people in my database.

We actually need to make the calendar to wrap around: to build a condition that would select 1904, Jan 1st after 1904, Dec 31th.

We can do it using a COALESCE on the simple queries in OUTER APPLY clause.

Let's create sample tables:

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Written by Quassnoi

August 21st, 2009 at 11:00 pm

Posted in SQL Server