PHP error with Mysql

Question

I’m making a mistake, and I don’t understand why. The mistake:

Fatal error: Call to a member function fetch_assoc() on boolean

the excerpt from the error:

require 'conecta.php';
    $sql = "SELECT `nomep`, `endereco` FROM `cadastropn` WHERE `cidade` = Caxias do Sul";
    $result = mysqli_query($mysqli, $sql);
    while($linha = $result->fetch_assoc()) {
        echo '<article>' . $linha['nomep'];
        $nome = $linha['nomep'];
        echo '</article>';
    }

The strange thing is that the mistake only happens when I put the WHEREcity= Caxias do Sul";

Answer 1

The mistake is because mysqli_query FALSE, so in error appears BOLEAN (that is not the type expected to fetch_assoc).

The reason is that Caxias do Sul is a string and has it in quotes. It should look like this: 'Caxias do Sul'.

Altere of:

$sql = "SELECT `nomep`, `endereco` FROM `cadastropn` WHERE `cidade` = Caxias do Sul";

To:

 $sql = "SELECT `nomep`, `endereco` FROM `cadastropn` WHERE `cidade` = 'Caxias do Sul'";