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• constraints
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• Saving the whole team of players or nothing

  Suppose that you need to store teams of players, and you must enforce the following business rule: each team must consist of exactly two players. I will demonstrate how you can use constraints to implement this rule. I haven't used this approach in production Read More... Posted Wednesday, July 15, 2009 2:28 PM by Alexander Kuznetsov | 0 Comments Filed under: Transact SQL, Business rules, constraints

• Two suggestions to enhance constraints in SQL Server

  We can tuck any logical expressions in CHECK constraints, but all foreign keys are currently capable of right now is to verify that one or more column values are equal. In many cases it would be very useful to have foreign keys use more complex logical Read More... Posted Monday, May 04, 2009 11:29 PM by Alexander Kuznetsov | 3 Comments Filed under: SQL Server, Transact SQL, Data Integrity, Business rules

• Using ROWVERSION to enforce business rules

  Suppose that you need to enforce the following business rule: contracts cannot be changed after you have started working on them (let us assume that that particular business operates in the perfect world). You can use a ROWVERSION column, a persisted Read More... Posted Tuesday, April 28, 2009 10:46 PM by Alexander Kuznetsov | 8 Comments Filed under: SQL Server, Database Programming, Transact SQL, Business rules