March blog post @All Analytics:
To ensure sensible results from and correct
interpretations of analysis of data from SQL tables or extracts thereof,
analysts must know the tables’ interpretation -- the business rules
underlying them -- which is rarely documented.
They should be represented in the database by
integrity constraints
-- not perfect substitutes, because they are very loose approximations
to the rules -- but if they are enforced in the database by the DBMS
they are usually recorded either in the definition statements that
created the tables and constraints, or the database catalog.
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