PHP OOP Help - Work In Progress - php

Question

I am right now trying to write a PHP class that executes database information. Yet I feel like I am doing something majorly wrong! It seems like what you would have to type in to get it to work is too much. Here is a example of what it looks like:
<?php
class database {
public $query_type = "";
public $database_name = "";
public $database_items_query = array();
public $database_where = "";
public function __construct($query_type, $database_name, $database_items_query, $database_where) {
$this->query_type = $query_type;
$this->query_name = $query_name;
$this->query_items_query = $query_items_query;
$this->query_where = $query_where;
}
public function database_query($query_type, $database_name, $database_items_query, $database_where) {
if ($query_type == "select") {
return $sqlquery = "SELECT ($database_items_query) FROM $database_name WHERE $database_where";
}
elseif ($query_type == "update") {
return $sqlquery = "UPDATE $databasename ";
}
}
}
$username = new database("");
?>
So for the beginning you would have to type in just this to get it to work the first function?
$username = new database("select","users","username","id");
So basically with what I have so far, what am I doing wrong? Sorry if this does not make sense :(

Answer 1

Ok I can see what you are trying to do, A constructor is normally used to "Create" a object. When the object is created then you have the opportunity to store values inside it so you dont have to
re-enter them, You only have to call a constructor once in a objects lifetime, and you can reuse all the methods multiple times.
soo... if you change your method declaration for database_query to something along these lines:
public function database_query($database_items_query = $this->database_items_query, $database_where = $this->query_where) {
$query_type = $this->query_type;
$database_name = $this->database_name;
Then you would be using the class variables as default values so your code would be something along the lines of
$columns = array("Name","Description");
$db = new database("SELECT","my_db",$columns,"1=1");
$db->database_query(); // returns name and description from all rows
$db->database_query(array("*") ); // returns all columns and rows
$db->database_query(array("*"),"id=7"); // returns all columns where id = 7
$other_db = new database("SELECT","my_other_db",$columns,"1=1");
$db->database_query(array("id") ); // calling database_query on first object instance
$other_db->database_query(array("*") ); // calling database_query on second object instance
When using objects/classes you have to remember that you can declare variables which belong to a given instance of the object so you can re
Dunno about you but when I was your age I was writing a fair bit of C, and to get introduced to OO I was described classes as being structs with function pointers inside.
If trying to learn OO I would reccomend taking a look at java since there is a lot of first principals OO stuff out there, then once comfortable with that style of code
taking what you have learned across to the language which you know a bit better (in your case PHP.)