Querying a database with oop - php

Question

I have connected to a database for the first time with oop and stright away come up with an issue, below is my code which i'm struggling with:
$q = 'SELECT * FROM test';
$sqli->query($q);
if($sqli->query($q)){
echo "worked";
}
if($sqli->error){
echo $sqli->error;
}
I have checked for errors when connecting to the db and that works fine, but when I run this query I get no output, why? I expected an error or "worked", but have got neither.
Whats happening?

Answer 1

I have put some comments in the source code to help:
$q = 'SELECT * FROM test';
//$sqli is the result of a
//new mysqli("localhost", "user", "password", "database");
$resource = $sqli->query($q); // this returns a resource or false
if(!$resource) {
echo $sqli->error;
die; // do not process further
}
// process the results
$rows = $resource->fetch_all();
if ($rows) { // check if there are rows
echo "worked";
}
else {
echo "query is ok, but there are no rows";
}

Answer 2

You could also use $resource->fetch_object() which returns an object for output. Therefore if you wanted to print specific data from the result set, you would do something like
//table test.Name and test.Country
while ($rowobj = $resource->fetch_object()){
printf ("%s (%s)\n", $rowobj->Name, $rowobj->Country);
}
Good luck,

Answer 3

You could use this method, I hope it's what you are looking for. You will need to define the DB first. Then you can connect in OOP and test the connection is true or exit();
Let me know if this works for you. You can also define the DB in an external file and just do an include(); towards the top of your script for any pages needing connection to the DB.
define("SERVER","IP Address");
define("USER","DB USERNAME");
define("PASSWORD","DB PASSWORD");
define("DATABASE","DB NAME");
// This is for connection
$mysqli = new mysqli(SERVER, USER, PASSWORD, DATABASE);
if ($mysqli->connect_errno) {
echo "Connection to MySQL failed: (" . $mysqli->connect_errno . ") " . $mysqli->connect_error;
exit();
}