On Sun, Feb 10, 2002 at 10:01:45PM -0600, Paul DuBois wrote: > At 18:07 -0800 2/10/02, Jeremy Zawodny wrote: > >On Sun, Feb 10, 2002 at 02:53:53PM -0500, Matthew Dougherty wrote: > >> If I use a REGEXP query on an indexed column using something like: > >> Field REGEXP '^A|^B|^C' > >> > >> Will MySQL use the index like it would if I used Field LIKE 'A%' or > >> Field LIKE 'B%' or FIeld LIKE 'C%' ?? > > > >It will not. > > > >Regular expressions are best used when you need something more complex > >than what "%" allows you to achieve. > > Not to mention that an index won't be used even for the LIKE expression, > because it uses OR. At least, I think it won't be.
Hm. It looks like it will in 4.0.2, at least: mysql> describe S2H; +------------+-------------+------+-----+---------+-------+ | Field | Type | Null | Key | Default | Extra | +------------+-------------+------+-----+---------+-------+ | Symbol | varchar(75) | | PRI | | | | HeadlineId | int(11) | | PRI | 0 | | +------------+-------------+------+-----+---------+-------+ 2 rows in set (0.06 sec) mysql> explain select * from S2H where Symbol like "y%" or Symbol like mysql> "c%"; +-------+-------+---------------+--------+---------+------+--------+------------+ | table | type | possible_keys | key | key_len | ref | rows | mysql> Extra | +-------+-------+---------------+--------+---------+------+--------+------------+ | S2H | range | Symbol | Symbol | 75 | NULL | 129617 | where used | +-------+-------+---------------+--------+---------+------+--------+------------+ 1 row in set (0.06 sec) Jeremy -- Jeremy D. Zawodny, <[EMAIL PROTECTED]> Technical Yahoo - Yahoo Finance Desk: (408) 349-7878 Fax: (408) 349-5454 Cell: (408) 685-5936 MySQL 3.23.47-max: up 3 days, processed 128,435,474 queries (409/sec. avg) --------------------------------------------------------------------- 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
