MySQL percent symbol?

Question

I have these lines in a php script to query the DB.

$rs_menucategories = mysql_query('SELECT `MenuCategoryID`, `MenuCategoryName` FROM `universitymenucategory`');

$q_menuitems = 'SELECT `MenuCategoryID`, `Order`, `ItemName`, `ItemCost`, `ItemDescription`'

. ' FROM `universitymenu`'

. ' WHERE `MenuCategoryID` = %d'

. ' ORDER BY `Order` ASC';

The only reference I can find for using %d is date formatting.

What exactly is %d doing here? Nothing in this query has anything to do with date.

Many thanks

Answer 1

"where x = "%d" means that the field "x" must end with the character "d"

"where x = "%d%" means that the field x must contain the character "d" anywhere.

It is not a reliable query in all mySQL versions.

The preferred method is " x LIKE '%d'

(not the "=" sign).

EDIT: sorry kingmaxi: "$q_menuitems " IS a mysql query!

Answer 2

It's a PHP thing, not a MySQL thing. The '%d' is used later on in the script (I found something similar on the web) in the line:

$rs_menuitems = mysql_query(sprintf($q_menuitems,

$crow['MenuCategoryID']));

The sprintf() function replaces the '%d' with the value in $crow['MenuCategoryID'] at that point to form the full mysql query. The %d simply tells sprintf it's going to be accepting a number as it's replacement value.

Hope that makes sense!

EDIT: Just JR, $q_menuitems is not a query at that point it's just a string. You can find a continuation of the script here that shows where the sprintf() function is used to replace the %d with a value contained in a query row:

http://www.dynamicdrive.com/forums/showt...