Path: csiph.com!v102.xanadu-bbs.net!xanadu-bbs.net!news.glorb.com!news-in-01.newsfeed.easynews.com!easynews!core-easynews-01!easynews.com!en-nntp-14.dc1.easynews.com.POSTED!not-for-mail From: Robert Wessel Newsgroups: comp.programming.threads,comp.programming Subject: Re: HashDbase and parallel hashlist... Message-ID: References: X-Newsreader: Forte Agent 6.00/32.1186 MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Lines: 39 X-Complaints-To: abuse@easynews.com Organization: Forte Inc. http://www.forteinc.com/apn/ X-Complaints-Info: Please be sure to forward a copy of ALL headers otherwise we will be unable to process your complaint properly. Date: Wed, 16 Jan 2013 19:03:52 -0600 X-Received-Bytes: 2203 Xref: csiph.com comp.programming.threads:1292 comp.programming:2834 On Wed, 16 Jan 2013 15:35:48 -0800, aminer wrote: > >Hello, > > >If you ask me the following question: > >Amine, why not support SQL joins etc. in HashDbase ? > > >Well i have to write an SQL parser that parser for exemple >the BNF of the follwing SQL statement for exemple: > >"select ed_lname >from editors, titleeditors >where editors.ed_id = titleeditors.ed_id >and titleeditors.title_id = 'PC8888'" > >Now the parser that i have to write must validate >this SQL statement first against the SQL BNF of this SQL statement, >and after that it has to split the SQL statement >into mutiple parts, the first part is the "select ed_lname" >and extract with a BNF the "ed_lname" field that we have >to return, and after that we have to parse with a BNF the >"from editors, titleeditors" to extract both the "editors" and >"titleeditors" tables, and after that we have to parse with >a BNF the "where...." part and after that we have to do >the computing part to return the ed_lname fields. > > >So the very important part to support the joins is to write an SQL parser. > >So if i have time to write this project i will support with a parser a >small subset of SQL first. The parser shouldn't be a big deal, the language is not that complex. A reasonable optimizer, OTOH, *is* a big deal.