Help avoiding query in loop

[ryanyork]

Hello, I am new here and to php. I have built a gradebook that has 4 tables.

users
|id|name|

category
|id|name|

questions
|id|question|answer|categoryid|

answers
|id|userid|questionid|studentanswer|

The goal is to show each student as the first column and each question in a selected category as the first row.

I have been successful doing this by creating a for loop, looping through each user and then executing a query for all the answers matching that user.

I know this is bad practice and very slow, I am trying to execute this without querying inside of the loop.

Right now my code is:

$sql = 'SELECT users.id, users.name, answers.answer, answers.userid, answers.questionid, questions.id, questions.question, questions.answer, questions.categoryid 
	  FROM users 
	  INNER JOIN answers ON answers.userId = users.id
	  INNER JOIN questions ON questionId = questions.id
	  WHERE mid = 3';
	  $result = $pdo->query($sql);
	  foreach ($result as $row){
		$grade[] = array(
		'id' => $row['id'],
		'name' => $row['firstName'],
		'answer' => $row['studentAnswer'],
		'correctAnswer' => $row['cans'],
		'question' => $row['question']
		);

This works well to create a table of each entry, but I need one row per student.

How can this be done with out creating many queries inside of a loop?