Paul, Thanks for the answers. As a matter of fact, I did think that I was issuing multiple queries at the same time. Thanks for the clarification.
---> Jonathan -----Original Message----- From: Paul DuBois [mailto:[EMAIL PROTECTED] Sent: Monday, March 03, 2003 9:29 PM To: [EMAIL PROTECTED]; [EMAIL PROTECTED] Subject: Re: Querying for performance... At 13:19 -0600 3/31/03, Jonathan Villa wrote: >All, > >I have been writing my applications using PHP/MySQL for about a year and >a half now. During this time and up to now, there hasn't been anything >wrong with my apps; however, I need to know if what I am doing is the >best route for optimal performance. > >So I ask these questions: > >1. How many queries can MySQL handle? > For example, one of my functions does this: > While (I am selecting some data) > { > while (use one of the results as an element to query a >different table) > { > echo the results formatted in html > } > } > I'm sure that I could be using a join, but this is an example. You're probably thinking that you're issuing multiple queries simultaneously when you're doing that, but unless you're playing tricks with buffering, you're not. By the time you get to the while loop ("selecting some data"), the first query has already been processed completely and the entire result set has been received on the client end. The server's done with it by the time you start issuing queries inside the loop. > >2. I am under the impression that a char is 'a character', but I >have read and think I have seen it used with more than one character. >For example, char (5). If this is correct, how many values can char >hold? CHAR(5) means a 5-byte char column. That is, a column that can hold up to 5 bytes of character data. For single-byte character sets (the usual case), that means 5 characters. >3. Is it true that varchar appends spaces to the value if it's not >all set? For example, if a varchar is set to 255 and my value is really >only 245, then 10 whitespaces will be appended to the original value. No, this is false for VARCHAR. It's true for CHAR in the sense that for a CHAR(255) column, 255 bytes will always be store. VARCHAR only stores as many bytes as needed, after trailing spaces, if any, are removed. > >-Jonathan --------------------------------------------------------------------- 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 --------------------------------------------------------------------- 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
