CASE Expression Family
Abstract
SQL is declarative, so we do not have the concept of flow control in procedural languages. Instead, we use expressions that come from primitive recursive function theory to select a result from among possible values.
Keywords
CASE expression
CASE expressions with GROUP BY
CHECK() clauses
COALESCE()
ELSE
Material implication
NULLIF()
Smisteru transform
THEN
WHEN
SQL-92 added new expressions and extended the rules for old ones to make the language more orthogonal. Basically, anything that looks reasonable is probably legal syntax. But SQL is declarative, so we do not have the concept of flow control in procedural languages. Instead, we use expressions that come from primitive recursive function theory ...
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