问题

Here is my script:

try {

    $stmt = $db_con->prepare(" INSERT INTO mytable ( col ) VALUES ( ? ) ");
    $inserting = $stmt->execute( array('anything') );

    if ( $inserting ) {
        echo 'successful';

    } else {
        echo 'failed';
    }

} catch(PDOException $e){ 

    echo 'failed';
}

What's my question: All I want to know, else and catch are the same in my script? In other word when else executes?

I think else never executes, because if $inserting == false then it jumps to the catch block, then else never run. Am I right? Writing that else is useless?

回答1:

It depends.

Most of time you don't want to know if a particular insert failed. But rather if your site is working all right or not. So in general your code should be just

$stmt = $db_con->prepare(" INSERT INTO mytable ( col ) VALUES ( ? ) ");
$stmt->execute( array('anything') );
echo 'successful';

with both else and catch being useless.

However, sometimes you may want catch a certain error. In this case use catch. Here is a code from my article:

try {
    $pdo->prepare("INSERT INTO users VALUES (NULL,?,?,?,?)")->execute($data);
} catch (PDOException $e) {
    if ($e->getCode() == 1062) {
        // Take some action if there is a key constraint violation, i.e. duplicate name
    } else {
        throw $e;
    }
}

here you may catch a certain error and handle it.

回答2:

Firstly i'll suggest you use

if($inserting->rowCount()==1){
    echo 'successful';
} else {
    echo 'failed';
}

to find out if it actually inserted.

The else statment is not useless. If your query doesnt insert due to a pdo error, then the catch statement will catch the error. But if it doesnt insert without any pdo errors and number of rows is 0 then the else statement will run

回答3:

Try a different output

If you're trying to work out which block is executing, the simplest idea would be to change what's echoed based on which block you hit.

try {
    if (...) {
        ...
    } else {
        echo "Failed: Some Message";
    }
} catch (Exception $e) {
    echo "Failed: Some Other Message";
}

Alternatively, you can put a logger function, or some other debug function.

来源：https://stackoverflow.com/questions/37343185/how-to-check-whether-inserting-fails

标签

php