From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
---|---|
To: | tom <tom(at)tacocat(dot)net> |
Cc: | Postgresql <pgsql-general(at)postgresql(dot)org> |
Subject: | Re: SQL WHERE: many sql or large IN() |
Date: | 2007-04-06 19:33:48 |
Message-ID: | 16762.1175888028@sss.pgh.pa.us |
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Lists: | pgsql-general |
tom <tom(at)tacocat(dot)net> writes:
> I've never seen this before.
> Is this PG specific or generic SQL that I've never been exposed to?
It's in the SQL standard. SQL92 saith
<table value constructor> ::=
VALUES <table value constructor list>
<table value constructor list> ::=
<row value constructor> [ { <comma> <row value constructor> }... ]
and lists this as an alternative to <query specification> (ie, a SELECT)
in the query grammar. So you can write VALUES anywhere you could write
SELECT. However, the spec also allows "entry level SQL" implementations
to dumb it down pretty far:
1) The following restrictions apply for Intermediate SQL:
a) A <table value constructor> shall contain exactly one <row
value constructor> that shall be of the form "(<row value
constructor list>)".
b) A <table value constructor> shall be the <query expression>
of an <insert statement>.
2) The following restrictions apply for Entry SQL in addition to
any Intermediate SQL restrictions:
None.
What we had up to 8.2 was the entry-level definition. I couldn't tell
you which other DBMSes support the full definition...
regards, tom lane
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