Every day you learn something new in PHP. For example, did you know the difference between the single quote ‘ and the double quote “?

When you use the single quote the string will be taken exactly as it is but if you use the double quote the string will be evaluated e.g.


$value = 100;

echo 'The value is $value'; // The value is $value` 

echo "The value is {$value}"; // The value is 100. The 
                  // {} are optional but nice to have 
                  // for readability

This nuance is especially important when writing SQL statements that have variables (a bad habit, by the way, you should be using prepared statements). So be careful and always wrap your SQL statements in double quotes when you are passing variables e.g.


$sql = $connection->query("SELECT * FROM users 
WHERE email='{$email}'"); // will pass actual 
                          // variable held by $email

$sql = $connection->query('SELECT * FROM users 
WHERE email=$email'); // will pass $email which 
                      // will return an error when you 
                      // need to parse the query result