Database Queries with PDO in PHP

The variable $pdo, which we obtained after connecting to the database, is an OOP object. This object has a special method query that executes SQL queries. Let's make a test query to our table:

php<?php
  $res = $pdo->query('SELECT * FROM users');
?>

The variable $res will store the query result. To get one row from the result, you need to use the method fetch:

php<?php
  $row = $res->fetch();
  var_dump($row); // first row
  
  $row = $res->fetch();
  var_dump($row); // second row
  
  $row = $res->fetch();
  var_dump($row); // third row
?>

When the rows run out, the method will return null. Therefore, it is convenient to get rows in the following loop:

php<?php
  while ($row = $res->fetch()) {
    var_dump($row);
  }
?>

For example, let's output user names in separate paragraphs:

php<?php
  while ($row = $res->fetch()) {
    echo '<p>' . $row['name'] . '</p>';
  }
?>

Let's put all the code together:

php<?php
  $res = $pdo->query('SELECT name FROM users');
  
  while ($row = $res->fetch()) {
    echo '<p>' . $row['name'] . '</p>';
  }
?>