July 2010
Intermediate to advanced
840 pages
16h 33m
English
Content preview from Joe Celko's SQL for Smarties, 3rd Edition
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25.3. Matrix Operations in SQL
A matrix is not quite the same thing as an array. Matrices are mathematical structures with particular properties. We cannot take the time to discuss them here; you can find the necessary information in a college freshman algebra book. Though it is possible to do many matrix operations in SQL, it is not a good idea; such queries and operations will eat up resources and run much too long. SQL was never meant to be a language for calculations.
Let us assume that we have two-dimensional arrays that are declared as tables using two columns for subscripts, and that all columns are declared with a NOT NULL constraint.
The presence of NULLs is not defined in linear algebra, and I have no desire to invent a three-valued ...
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