Question

I have asked a question about how to retrieve data from different tables in sql How to get data from 4 tables in 1 sql query?

When I run the query for my sample data I get 3 rows, anyway being many-to-many relationship between courses and categories I will always get more rows for same course.

My question is how do I handle this data in PHP? I get an array and what I want would be something like:

Array ( 
  [0] => stdClass Object ( 
      [name] => course name 
      [tutor] => tutor name 
      [categories] => Array ( categories here ) 
);

Should I just fetch the data from the categories in a foreach loop after I fetch a course? That would mean bad performance for large amount of data.

Answer 1

Should I just fetch the data from the categories in a foreach loop after I fetch a course? That would mean bad performance for large amount of data.

I think that depends on what you will do with the data. If it’s just to show to user, i think it’s a good idea paginate the results.

But if you really need to fecth all data in one query and store this in one big array, you can do something like this:

$last_id = -1;
for( $x=0; $x < count($myArray); $x++ ) {
  if( $last_id != $myArray[$x]['id'] ) {
    //course changed, do something!
  } 
  //do more stuff...
  $last_id = $myArray[$x]['id'];
}