sql tables

From: paul c <toledobythesea_at_ooyah.ac>
Date: Thu, 11 Oct 2007 15:21:08 GMT
Message-ID: <EbrPi.13483$Da.2157_at_pd7urf1no>

(note, I changed the thread subject)

Bob Badour wrote:
> David Cressey wrote:
> ...

>> An SQL DBMS manipulates tables,  not relations or relational variables.

> Exactly.

I presume David could just as well have said "an SQL DBMS manipulates SQL tables". Found (finally) a copy of some draft or other of the SQL standard at http://www.contrib.andrew.cmu.edu/~shadow/sql/sql1992.txt .

Not sure how this copy might differ from the official ones, but anyway, here's some of what it says in section 4.9 which seems to be about "Concepts":

> 4.9 Tables
> A table is a multiset of rows. A row is a nonempty sequence of
> values. Every row of the same table has the same cardinality and
> contains a value of every column of that table. The i-th value in
> every row of a table is a value of the i-th column of that table.
> The row is the smallest unit of data that can be inserted into a
> table and deleted from a table.

I'm wondering if there are popular SQL dbms's that follow this. For example, do any of them let me "insert", say, two "rows" that would be considered the same row if a table were a set of rows rather than a multiset of rows, giving, eg.:


Also wondering about "i-th" values in rows. Does the above also mean that

ColumnA ColumnB
1 2

is not equal to

ColumnB ColumnA

2 1

(all other things being equal)? Received on Thu Oct 11 2007 - 17:21:08 CEST

Original text of this message