用oop查询数据库

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"; 
   }