How can I retrieve a field in mysql table from a variable from a previous query? I have been trying a structure that looks like this: Query A) OOP php to get 1st result set: $q = "SELECT id, label, parent FROM mytable"; process associative array in while loop, and display this to page (call it parent) with: instantiating the object: $obj = new myclass(); and then: echo $obj->display_myfunction(); B) So where I get lost is adding a second query to get other fields in the same table related to the id from query $q. Can I write a second query that goes something like: $y = "SELECT id, parent FROM mytable where this->id = id"; provided that both queries A & B are in the same class? I imagine a situation where A) is a menu bar down the left side of a page, and what is active in the menu is displayed in B) on the body of the page.
You're on the right track but I'm not quite sure where the problem is. When putting the variable into the new query (which is just a string until it hits the database) code it like this $y = "SELECT `id`, `parent` FROM `mytable` where `id` = '{$this->id}'"; // or $y = "SELECT `id`, `parent` FROM `mytable` where `id` = '".$this->id."'"; PHP: The {} tell PHP to look for a variable - forced rather than implied and necessary for objects and arrays otherwise it stops at -> and doesn't read the rest. The `` around the table name and column name are to ensure mysql knows the name relates to a column or table and doesn't get confused with reserved words. Best practice and not essential.