MySQLi OOP Class Insert Function Not Working - php

Question

I am currently practicing OOP, creating a MySQLi class that will have atleast the basic MySQLi functions (insert, select, update, etc). This is what I have got so far:
if(!class_exists('dbc')) {
class dbc {
public function __construct($host = host, $username = username, $password = password, $database = database) {
// Make the constants class variables
$this->host = host;
$this->username = username;
$this->password = password;
$this->database = database;
$this->connection = new mysqli($this->host, $this->username, $this->password, $this->database);
if($this->connection->connect_errno) {
die('Database connection error!');
return false;
}
}
public function __deconstruct() {
if($this->connection) {
$this->connection->close();
}
}
public function insert($table, $variables = array()) {
if(empty($table) || empty($variables)) {
return false;
}
$sql = "INSERT INTO $table ";
$fields = array();
$values = array();
foreach($variables as $field => $value) {
$fields[] = "'" . $field . "'";
$values[] = "'" . $value . "'";
}
$fields = '(' . implode(', ', $fields) . ')';
$values = '(' . implode(', ', $values) . ')';
$sql .= $fields . ' VALUES ' . $values;
$query = $this->connection->query($sql);
if(!$query) {
echo mysqli_error($this->connection);
}
echo $sql;
}
}
}
As you can see, I create the connection via the details from the config file, I then send a query through the established connection. But for some reason when I attempt to create a MySQLi insert query, I just get the same error over, and over again:
You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near ''name', 'option') VALUES ('Sub Title', 'This is a test website')' at line 1
I even echoed out the sql query, which appeared to be the correct format:
INSERT INTO options ('name', 'option') VALUES ('Sub Title', 'This is a test website')
I have spent hours of Googling, trial and error, etc, trying to fix this, and have had no luck, and as it's 12:30am, I'm tired and may be missing something critical, so if anyone knows what is causing this problem, it'll be greatly appreciated for a solution, etc.
Thanks,
Kieron

Answer 1

The column names in the first set of parenthesis should not be quoted:
INSERT INTO options (name, option) VALUES ('Sub Title', 'This is a test website')
// ^^^^ ^^^^^^
Though you can use backticks ` around the column names e.g. `name`, `option`.

Answer 2

Your connection is definitely not working as you are missing the $ on these 4 lines infront of the parameter names
$this->host = host;
$this->username = username;
$this->password = password;
$this->database = database;
Should be
$this->host = $host;
$this->username = $username;
$this->password = $password;
$this->database = $database;
Also the name you have used for your class deconstructor is incorrect it should be
public function __destruct() () {
yours will not cause an error but it will not run automatically on class destruction with your name.
#Marty is correct about the use of backticks and not single quotes around your query syntax, but I dont see how the connection gets made based on the first error I mentioned, and therefore how you get a sensible SQL error reported, however something may be going on that is not obvious from the code you showed us.