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Another reminder note.
The RDBMS query engine relies on these laws to build efficient queries:
Commutation:
Numbers may travel (commute)
Association:
Numbers may freely associate
Distribution:
Operators can be distributed
A more general statement of these laws:
Commutative law:
Associative law:
Distributive law:
Date has an excellent discussion of all this on pp 124 – 127 of SQL and Relational Theory: How to Write Accurate SQL Code
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