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February 2007 - Posts

• Trouble with CHECK Constraints

  ANSI/ISO SQL defines CHECK constraints very simply as: <check constraint definition> ::= CHECK <left paren> <search condition> <right paren> where <search condition> is a boolean expression, including query expressions. In Read More... Posted 19 February 2007 18:36 by David.Portas | 3 Comments Filed under: SQL, SQL Server

• More on Disjoint Subtypes

  My post on Disjoint Subtypes generated some interesting feedback. I made a point of saying that the Products table in my schema is in BCNF. That’s because the only determinants are supersets of {SKU}, which is the only key. The point I wanted to Read More... Posted 19 February 2007 13:24 by David.Portas | 0 Comments Filed under: SQL, Data Modelling