Question

Below is part of a PHP database class someone else wrote, I have removed about 80% of it’s code, all the un-related code to my question has been removed and just the amount remains that allows me to test this class without actually hitting a real database.

This class has a couple methods that let you set a key and value it then turns it into a mysql UPDATE and INSERT sql query using an array. I am trying to figure out how to use this code 100% so I can use this feature of it for UPDATE and INSERTS in my own application.

Basicly from what I gather you do something like this…

// assign some key/values to insert into DB
$db->assign('name', 'dfgd');
$db->assign('age', 87);
$db->assign('sex', 'female');
$db->assign('user_id', 4556);

// Do  the insert
$db->insert('testing2');

Now where I am confused is I can keep on running code like this over and over on the page and it always will use the correct set of key/value array sets. Above you can see I used the assign() method 4 times and then call the insert() method which creates this

INSERT INTO test (name, age, sex, user_id) VALUES (jason davis, 26, male, 5345)

Now if I run another set like this on the same page…

// assign some key/values to insert into DB
$db->assign('name', 'dfgd');
$db->assign('age', 87);
$db->assign('sex', 'female');
$db->assign('user_id', 4556);

// Do  the insert
$db->insert('testing2');

It then creates this…

INSERT INTO testing2 (name, age, sex, user_id) VALUES (dfgd, 87, female, 4556)

So how does it not combine the 2 sets of 4, so instead of inserting 8 record on the second insert, it completey replaces the first set of 4 values with the new set. This is great and what I want but I do not understand how it is happening? Also can this be improved anyway?

Below is a full class and my demo code, it can be ran without needing to connect to mysql for this demo, it will print to screen the SQL that it builds.

Also where would the public function reset() in the code below need to be used at, or would it not be needed?

<?php 
class DB{
    public $fields;

    public function assign($field, $value){
        $this->fields[$field] = ($value)==""?("'".$value."'"):$value;
    }

    public function assign_str($field, $value){
        $this->fields[$field] = "'".addslashes($value)."'";
    }

    public function reset(){
        $this->fields = array();
    }

    public function insert($table){
        $f = "";
        $v = "";
        reset($this->fields);
        foreach($this->fields as $field=>$value){
            $f.= ($f!=""?", ":"").$field;
            $v.= ($v!=""?", ":"").$value;
        }
        $sql = "INSERT INTO ".$table." (".$f.") VALUES (".$v.")";
        //print SQL to screen for testing
        echo $sql;
        //$this->query($sql);
        return $this->insert_id();
    }

    public function update($table, $where){
        $f = "";
        reset($this->fields);
        foreach($this->fields as $field=>$value){
            $f.= ($f!=""?", ":"").$field." = ".$value;
        }
        $sql = "UPDATE ".$table." SET ".$f." ".$where;
        echo $sql;
        //$this->query($sql);
    }

    public function query($_query){
        $this->query = $_query;
        $this->result = @mysql_query($_query, $this->link_id) or die( $_query."<p>".mysql_error($this->link_id) );
        return $this->result;
    }

    public function insert_id(){
        return @mysql_insert_id($this->link_id);
    }
}


// start new DB object
$db = new DB;

// assign some key/values to insert into DB
$db->assign('name', 'jason davis');
$db->assign('age', 26);
$db->assign('sex', 'male');
$db->assign('user_id', 5345);

// Do  the insert
$db->insert('test');


echo '<hr />';

// assign some key/values to insert into DB
$db->assign('name', 'dfgd');
$db->assign('age', 87);
$db->assign('sex', 'female');
$db->assign('user_id', 4556);

// Do  the insert
$db->insert('testing2');


echo '<hr />';

// assign some key/values to UPDATE the DB
$db->assign('name', 'jason davis');
$db->assign('age', 26);
$db->assign('sex', 'male');
$db->assign('user_id', 5345);

// DO the DB UPDATE
$db->update('blogs', 'WHERE user_id = 23');

?>

Answer 1

insert() and update() should (originally) set the $this->fields property back to an empty array upon execution, but you somehow (wrongly) deleted that code?

Update your code to this:

    public function insert($table){
        $f = "";
        $v = "";
        foreach($this->fields as $field=>$value){
            $f.= ($f!=""?", ":"").$field;
            $v.= ($v!=""?", ":"").$value;
        }
        $sql = "INSERT INTO ".$table." (".$f.") VALUES (".$v.")";
        $this->reset();
        //print SQL to screen for testing
        echo $sql;
        //$this->query($sql);
        return $this->insert_id();
    }

    public function update($table, $where){
        $f = "";
        foreach($this->fields as $field=>$value){
            $f.= ($f!=""?", ":"").$field." = ".$value;
        }
        $sql = "UPDATE ".$table." SET ".$f." ".$where;
        $this->reset();
        echo $sql;
        //$this->query($sql);
    }