On Fri, 16 Sep 2016 16:59:17 +0200
Dominique Devienne <ddevie...@gmail.com> wrote:
> Is that <<WHERE col IN tab>> SQL standard?
The two most frequently used pointless words in SQL are "select *".
The SELECT clause (not statement) chooses columns; in relational
algebra terms, it's a project operator. If "all columns" is what you
need, what you don't need is projection. Requiring "select *" makes as
much sense as requiring "WHERE TRUE" if there is no restriction.
The strict select-from-where construct in SQL is an artifact of its
roots in IBM's 1970s-era "4th generation" languages. That's why the
language looks so much like Cobol and so little like math.
But it is what it is. In SQL, a tablename is a parameter for FROM (and
nowadays, JOIN). Predicates -- IN, EXISTS -- take SELECT.
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