从数据库中选择任何项目都不返回1，为什么？

Question

Hello I have three small questions... I have this following query on mysql in my php... it delivers me the value 0 after selecting, even there is no bla = $bla - it should deliver me no value, why it deliveres me 0?

second question: the result is 1 - why does the selection succeed, even there is no bla = $bla?

third question: how can I know the selection wasn't succeded due to no item was selected because the WHERE condition did not succeeded.

$stmt= $this->conn->prepare("SELECT id FROM column WHERE bla = ?");
    $stmt-> bind_param("s", $bla);

        $result = $stmt->execute();
        $result = $stmt -> bind_result($id);

        echo $result;

Answer 1

In your code. $result is the result of the query execution. It is not the data from the SQL statement.

execute returns a boolean. See: http://php.net/manual/en/mysqli-stmt.execute.php