Re: Aggregation is Inverse of Join
From: paul c <toledobythesea_at_oohay.ac>
Date: Mon, 15 Jan 2007 22:58:58 GMT
Message-ID: <SGTqh.658799$1T2.620722_at_pd7urf2no>
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> I think the usual term is "extend."
>
> In the relational lattice, project is just a specialization of the
> inner union, with one of the operands having cardinality zero.
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>
> Marshall
>
Date: Mon, 15 Jan 2007 22:58:58 GMT
Message-ID: <SGTqh.658799$1T2.620722_at_pd7urf2no>
Marshall wrote:
> On Jan 15, 8:41 am, "Walt" <wami..._at_verizon.net> wrote:
>
>>"Marshall" <marshall.spi..._at_gmail.com> wrote in >> >> >>>Well, I've run out of steam. More later. >> >>>Marshall >> >>>PS. I told you I wasn't organized.
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>>Interesting. It's going to take me weeks to get it. >> >>In the meantime, what is the inverse of Project?
>
>
> I think the usual term is "extend."
>
> In the relational lattice, project is just a specialization of the
> inner union, with one of the operands having cardinality zero.
>
>
> Marshall
>
Surely, it's join.
p Received on Mon Jan 15 2007 - 23:58:58 CET