Re: Looking for some relational algerba exercise(with answer)?
From: paul c <toledobythesea_at_oohay.ac>
Date: Sun, 26 Nov 2006 00:23:31 GMT
Message-ID: <785ah.371472$5R2.161597_at_pd7urf3no>
>
>
> Well, I'm not the original poster; but given that the "purpose" was to
> practice relational algebra, I'm guessing no: writing queries for
> Microsoft Access would not serve that purpose. In brief, I am convinced
> of that based mainly only on the fact that SQL and relational algebra
> are not the same thing. Writing queries in relational algebra might
> serve the purpose; but I suspect the original request was for
> interesting questions (perhaps simplification?), rather than just "write
> this query" rote work.
>
> Just a guess.
>
Date: Sun, 26 Nov 2006 00:23:31 GMT
Message-ID: <785ah.371472$5R2.161597_at_pd7urf3no>
Chris Smith wrote:
> Neo <neo55592_at_hotmail.com> wrote:
>
>>See >>www8.silversand.net/techdoc/teachsql/index.htm >>www.samspublishing.com/library/library.asp?b=STY_Sql_24hours&rl=1 >>have problems thru out the books and answers in the appendix. >> >>Would practicing those command in Microsoft Access, a common database >>for PCs, serve your purpose?
>
>
> Well, I'm not the original poster; but given that the "purpose" was to
> practice relational algebra, I'm guessing no: writing queries for
> Microsoft Access would not serve that purpose. In brief, I am convinced
> of that based mainly only on the fact that SQL and relational algebra
> are not the same thing. Writing queries in relational algebra might
> serve the purpose; but I suspect the original request was for
> interesting questions (perhaps simplification?), rather than just "write
> this query" rote work.
>
> Just a guess.
>
Even though it costs money, I'd think a good vendor-neutral textbook, such as CJ Date's Intro' to Database Systems is the best way to go, that way one's habits don't get polluted by vendor mistakes. Date's book gives answers to some of the questions, so you have some of a chance of seeing whether your thinking is on the right track. (Sometimes I think somebody should put one out with varied multiple answers, discussed, to all of Date's questions as was once done for the book on C that its inventors wrote.)
p Received on Sun Nov 26 2006 - 01:23:31 CET