Uncaught Error: Call to a member function fetchColumn () on boolean

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Uncaught Error: Call to a member function fetchColumn () on boolean

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Hello, why do I get that error? this function is to validate if there is a user or not but I get this problem:

Fatal error: Uncaught Error: Call to a member function fetchColumn () on boolean in C: \ xampp \ htdocs \ login_oracle \ funcs \ funcs.php: 50 Stack trace: # 0 C: \ xampp \ htdocs \ login_oracle \ registry.php (38): userExist ('ortega') # 1 {main} thrown in C: \ xampp \ htdocs \ login_oracle \ funcs \ funcs.php on line 50

function userExist ($ user) { global $ db;

        $num = $db->query("SELECT COUNT(*) FROM usuarios WHERE DEPARTMENT_ID=". $usuario)->fetchColumn(); //<<<<<<< AQUI ESTA EL PROBLEMA

        printf("<script type='text/javascript'>alert('LO DEVUELTO ES : $num'); </script>"); 

        if ($num != 0)
        {
            return true;
        } 
        else {
            return false;
        }
    }

I could use rowCount but since it is a select this in ORACLE does not work well, only with update, insert or stop. How else can I know the number of rows affected from the last select query I made in PDO ORACLE? or how can I solve that code error. thanks

php oracle

asked by RicardoBarros 12.12.2017 в 20:21

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2 answers

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score 1 · Answer 1

Your code has two problems:

It is vulnerable to SQL injection. To correct it, you must implement prepared queries.

You are not using fetchColumn well.

Apart from this, we will use other techniques, such as the ternary operators , to simplify the code .

Since you mention it in the question, rowCount you do not need it here, because what your query does is precisely to count the rows that there are.

I propose this solution:

    $strSQL="SELECT COUNT(*) FROM usuarios WHERE DEPARTMENT_ID=:id";
    $stmt = $db->prepare($strSQL);

    if ($stmt){
        /*Pasamos los datos aparte para evitar la Inyección de código malicioso*/
        $arrParams=array(":id"=>$usuario);
        $stmt->execute($arrParams);
        $num=$stmt->fetchColumn();
        /*El operador ternario permitirá hacer la evaluación una sola vez*/
        $bolResultado=($num != 0) ? true : false;
        printf("<script type='text/javascript'>alert('LO DEVUELTO ES : $num'); </script>"); 

    }else{

        $bolResultado=false;                        
    }

    return $bolResultado;

score 0 · Answer 2

When the query does not return any result as an INSERT or has an error, I think it returns true or false.

you could validate it like this:

$query = $db->query("SELECT COUNT(*) FROM usuarios WHERE DEPARTMENT_ID=". $usuario);
if (!is_bool($query)){
   $num = $query->fetchColumn();
} else ...

Greetings.