THE SQL Server Blog Spot on the Web

Welcome to - The SQL Server blog spot on the web Sign in | |
in Search

Paul Nielsen

playing "Let's Pretend" with SSN data

The trouble with surrogate nulls (storing real data and pretending that it represents missing data) is that you never know when the real data is going to be interpreted as real data.

Here’s a twist on the surrogate null issue: a case of shorter SSN numbers from Micronesia being padded with leading zeros - presumably a software requirement – which comes causes all sorts of frustration for those with SSN numbers that actually do begin with zeros.


There are two lessons here:

First, respect data and don’t presume that real data can pretend to represent missing data, even for a few digits, without being found out eventually.

Second, data decisions should be made by a data architect with the experience to anticipate and prevent foolish errors.

Published Thursday, August 20, 2009 8:33 AM by Paul Nielsen
Filed under:



cinahcaM madA said:

I found the comments to be much more interesting than the actual story...

August 20, 2009 10:16 AM
New Comments to this post are disabled

About Paul Nielsen

Paul Nielsen believes SQL is the romance language of data. As such he’s a hands-on database developer, Microsoft SQL Server MVP, trainer, and author of SQL Server Bible series (Wiley). As a data architect, he developed the concepts of Smart Database Design and Nordic – an open source O/R dbms for SQL Server. He lives in Colorado Springs.
Privacy Statement