SSW Update - What sort of primary keys do you use - Natural or Surrogate?
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G'Day Developers!

Now this is a controversial one. Which one do you use?

  1. A "Natural" (or "Intelligent") key is actual data
    • Surname, FirstName, DateOfBirth
  2. An "Acquired Surrogate" (or "Artifical" or "System Generated") key is NOT derived from data eg. Autonumber
    • eg. ClientID 1234
    • eg. ClientID JSKDYF
    • eg. ReceiptID 1234
  3. A "Derived Surrogate" (or "User Provided") key is indirectly derived from data eg. Autonumber
    • eg. ClientID SSW (for SSW)
    • eg. EmpID AJC (for Adam Jon Cogan)
    • eg. ProdID CA (for Code Auditor)

The problems with Natural Keys:

  • Because they have a business meaning, if that meaning changes (eg. they change their surname), then that value NEEDS to changed. Changing a value with data is a little hard - but a lot easier with Cascade Update.
  • The main problem is that the key is large and combined and this needs to be used in all joins

The Problem with Acquired Surrogate Keys:

  • A surrogate key has no meaning to a user
  • It always requires a join when browsing a child table eg. The InvoiceDetail table

The Problem with Derived Surrogate

  • The user needs to enter a unique value
  • Because they have a business meaning, if that meaning changes (eg. they change their company name), then that value MAY NEED to changed. Changing a value with data is a little hard - but a lot easier with Cascade Update
  • More likely to have a problem with Merge Replication

So our recommendations are:

Sample code for the SSW Derived Surrogate:

Cheers until next time, Adam
SSW Chief Architect and Microsoft Regional Director, Australia 

Got a comment for Adam? 6164616d636f67616e407373772e636f6d2e6175

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