Re[4]: to_number question

From: Jonathan Gennick <jonathan_at_gennick.com>
Date: Thu, 15 Jul 2004 10:31:42 -0400
Message-ID: <153987283308.20040715103142@gennick.com>

Thursday, July 15, 2004, 10:06:04 AM, Wolfgang Breitling (breitliw_at_centrexcc.com) wrote:
>> 1. The subquery defines a *new* table of rows.

WB> No, it does not.

Ok. I've started to do a bit of digging in the 1999 ANSI SQL standard. Section 7.5 describes the FROM clause as containing a <table reference list>:

    FROM <table reference list>

    <table reference list> ::= <table reference> ...

Later, section 7.6 defines <table reference> as follows:

    <table reference> ::= <table primary> | <joined table>

<table primary> can be many things, one of which is a <derived table>, and a <derived table>, in turn, is defined as a <table subquery>.

The standard does seem here, to put a subquery in the FROM clause on an equal footing with a table that you specify by name. A subquery is simply another way of specifying a table.

Best regards,

Jonathan Gennick --- Brighten the corner where you are http://Gennick.com * 906.387.1698 * mailto:jonathan@gennick.com

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Received on Thu Jul 15 2004 - 09:28:25 CDT