At 1:24 -0600 4/6/02, BD wrote: >Paul, > Do you know if there is any performance differences between >a unique index and primary key (if there are no nulls)? > Is the index file format the same as the primary key?
I cannot answer that with absolute certainty, but as far as I know the answers are no, and yes. > >Brent > >At 05:09 PM 4/5/2002, you wrote: >>>Here are a few easy philosophical questions for a change: >>> >>>1) For performance or storage benefits, is there a difference between a >>>Unique Index and Primary Key? >> >>There can be only one primary key. There can be multiple unique indexes. >> >>Primary keys cannot contain NULL values. Unique indexes can allow NULL >>values (and in fact, NULL is the one value that can occur multiple >>times in a unique index). >> >>> >>>2) Is there a reason why I should use Primary Key instead of a Unique Index? >>> >>>3) Why isn't there a syntax for "create primary index index_name on >>>table_name (fieldlist)" ? I know a primary key can be added with "Alter >>>table", but if I'm defining indexes for a table, it would look a lot better >>>in the script if I was using the same syntax. >>> >>>TIA >>> >>>Brent >>> >>>sql, query --------------------------------------------------------------------- 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
