Primary Key vs Clustered Unique Index
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What am I giving up if instead of choosing a primary key when I design a table, I create a unique clustered index instead? What are the systemic differences?
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1) A primary key can be non-clustered.
2) A unique index will allow one null value. Of course, if the column is set to NOT NULL, it won't.
K. Brian Kelley
http://www.truthsolutions.com/
Author: Start to Finish Guide to SQL Server Performance Monitoring
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K. Brian Kelley
@kbriankelley -
Two different things. Logically. The PK is the unqiue identifier for the data row. A unique index preseves uniqueness in the column.
Physically they are implemented the same.
Steve Jones
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Thanks! Always looking for a better understanding of what's under the hood.
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