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copied!<p>I'll be up-front about my preference for natural keys - use them where possible, as they'll make your life of database administration a lot easier. I established a standard in our company that all tables have the following columns:</p> <ul> <li>Row ID (GUID)</li> <li>Creator (string; has a default of the current user's name (<code>SUSER_SNAME()</code> in T-SQL))</li> <li>Created (DateTime)</li> <li>Timestamp</li> </ul> <p>Row ID has a unique key on it per table, and in any case is auto-generated per row (and permissions prevent anyone editing it), and is reasonably guaranteed to be unique across all tables and databases. If any ORM systems need a single ID key, this is the one to use.</p> <p>Meanwhile, the actual PK is, if possible, a natural key. My internal rules are something like:</p> <ul> <li>People - use surrogate key, e.g. INT. If it's internal, the Active Directory user GUID is an acceptable choice</li> <li>Lookup tables (e.g. StatusCodes) - use a short CHAR code; it's easier to remember than INTs, and in many cases the paper forms and users will also use it for brevity (e.g. Status = "E" for "Expired", "A" for "Approved", "NADIS" for "No Asbestos Detected In Sample")</li> <li>Linking tables - combination of FKs (e.g. <code>EventId, AttendeeId</code>)</li> </ul> <p>So ideally you end up with a natural, human-readable and memorable PK, and an ORM-friendly one-ID-per-table GUID.</p> <p>Caveat: the databases I maintain tend to the 100,000s of records rather than millions or billions, so if you have experience of larger systems which contraindicates my advice, feel free to ignore me!</p>

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