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Minor wordsmithing.

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Tom Lane 2002-01-08 15:38:42 +00:00
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commit d09f6f7741
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doc/src/sgml/keywords.sgml
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<!-- $Header: /cvsroot/pgsql/doc/src/sgml/keywords.sgml,v 2.4 2001/11/17 13:27:16 petere Exp $ -->
<!-- $Header: /cvsroot/pgsql/doc/src/sgml/keywords.sgml,v 2.5 2002/01/08 15:38:42 tgl Exp $ -->
<appendix id="sql-keywords-appendix">
<title><acronym>SQL</acronym> Key Words</title>
@ -17,12 +17,13 @@
<para>
SQL distinguishes between <firstterm>reserved</firstterm> and
<firstterm>non-reserved</firstterm> key words. Reserved key words
<firstterm>non-reserved</firstterm> key words. According to the standard,
reserved key words
are the only real key words; they are never allowed as identifiers.
Non-reserved key words only have a special meaning in particular
contexts and can be used as identifiers in other contexts. Most
non-reserved key words are actually the names of built-in tables
and functions specified by SQL and the concept of non-reserved key
and functions specified by SQL. The concept of non-reserved key
words essentially only exists to declare that some predefined meaning
is attached to a word in some contexts.
</para>
@ -33,9 +34,9 @@
ranging from those that can never be used as an identifier to those
that have absolutely no special status in the parser as compared to
an ordinary identifier. (The latter is usually the case for
functions specified by SQL.) SQL reserved key words are not
functions specified by SQL.) Even reserved key words are not
completely reserved in <productname>PostgreSQL</productname>, but
can be used as column label (as in <literal>SELECT 55 AS
can be used as column labels (for example, <literal>SELECT 55 AS
CHECK</literal>, even though <token>CHECK</token> is a reserved key
word).
</para>
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known to the parser but are allowed in most or all contexts where an
identifier is expected. Some key words that are otherwise
non-reserved cannot be used as function or data type names and are
marked accordingly. (Some of these tokens represent built-in
marked accordingly. (Most of these words represent built-in
functions or data types with special syntax. The function or type
is still available but it cannot be redefined by the user.) Labeled
<quote>reserved</quote> are those tokens that are only allowed as
<quote>AS</quote> column label names (and perhaps in very few other
contexts). Some reserved key words are available as names for
contexts). Some reserved key words are allowable as names for
functions; this is also shown in the table.
</para>