Vertica Quick Tip: A Truly Unique Constraint

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Vertica Quick Tip: A Truly Unique Constraint

Post by JimKnicely » Mon Jan 29, 2018 4:50 pm

Vertica Community Blog post authored by Jim Knicely
According to the ANSI standards SQL:92, SQL:1999, and SQL:2003, a UNIQUE constraint should disallow duplicate non-NULL values, but allow multiple NULL values.

A Unique Constraint in Vertica does just that!

But what if I do not want to allow more than one NULL value? Well, there’s a simple trick for that!

Read about it here: ... onstraint/
Jim Knicely


Note: I work for Vertica. My views, opinions, and thoughts expressed here do not represent those of my employer.

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