David, Tuesday, April 16, 2002, 3:01:46 PM, you wrote: DA> Cards on the table, I have an assignment in soon and part of the DA> deliverable is to design some relational algebra tree's based on some DA> queries I have been given.
DA> This is one of the queries: DA> SELECT id DA> FROM Table1 DA> WHERE id NOT IN DA> (SELECT id DA> FROM Table2); DA> I have an idea that this query uses a left join after projecting id in DA> both tables. DA> If anyone can help me understand this a bit better, I would REALLY DA> appreciate an email from you. See: SELECT table1.id FROM table1 LEFT JOIN table2 ON table1.id=table2.id WHERE table2.id IS NULL; DA> Thanks lots DA> David Ayliffe -- For technical support contracts, goto https://order.mysql.com/ This email is sponsored by Ensita.net http://www.ensita.net/ __ ___ ___ ____ __ / |/ /_ __/ __/ __ \/ / Victoria Reznichenko / /|_/ / // /\ \/ /_/ / /__ [EMAIL PROTECTED] /_/ /_/\_, /___/\___\_\___/ MySQL AB / Ensita.net <___/ www.mysql.com --------------------------------------------------------------------- Before posting, please check: http://www.mysql.com/manual.php (the manual) http://lists.mysql.com/ (the list archive) To request this thread, e-mail <[EMAIL PROTECTED]> To unsubscribe, e-mail <[EMAIL PROTECTED]> Trouble unsubscribing? Try: http://lists.mysql.com/php/unsubscribe.php
