PDO Exception for each VS statement. Once for a transaction?

Question

I am going to implement transactions in my php scripts and I am doing some tests to help myself understand how they work. I have the following code snippet:

try{
    $db->beginTransaction();

    $update = "UPDATE persons SET first_name = 'Adam' WHERE person_id = 4";
    $stmt = $db->exec($update);


    $select = "SELECT person_id, column_that_doesnt_exist FROM persons";

    try{
        $stmt = $db->prepare($select);
        $stmt->execute();
        $rows = $stmt->fetchAll(PDO::FETCH_ASSOC);
        echo json_encode('success');
    } catch (PDOException $e) {
        echo 'execute failure';
    }

    echo ' code gets here';

    $db->commit();
} catch(PDOException $e){
    $db->rollBack();
    echo json_encode('commit failure');
}

which outputs:

execute failure code gets here

And the name of man 4 is updated to Adam.

Now I am sure that this is happening because the second request was never executed, because it was never executed, as it preparewas a point of failure.

It would be nice if it PDOExceptionwere thrown out for the latter catch, since it was added to the inside try, but I can get around this.

Now, if I pulled out "internal" tryand got this code:

try{
        $db->beginTransaction();

        $update = "UPDATE persons SET first_name = 'Adam' WHERE person_id = 4";
        $stmt = $db->exec($update);


        $select = "SELECT person_id, column_that_doesnt_exist FROM persons";


            $stmt = $db->prepare($select);
            $stmt->execute();
            $rows = $stmt->fetchAll(PDO::FETCH_ASSOC);


        $db->commit();
    } catch(PDOException $e){
        $db->rollBack();
        echo json_encode('commit failure');
    }

commit fails, db rolls back and displays commit failureas expected.

, try-catch try (), commit ? .... , ....

Answer 1

, try..catch, . , , , , .

, , . , , , , - .

, , . :

StartTransaction;
try {
  ModifyData;
  CommitTransaction;
}
catch {
  RollbackTransaction;
  // Log/mail/show/ignore error
}

, , .

, , :

StartTransaction;
try {

  foreach ($persons as $person) {
    try {
      ModifyPerson($person);
    }
    catch {
      throw new Exception("Updating person {$person->name} failed");
    }
  }

  CommitTransaction;
}
catch {
  RollbackTransaction;
  // Log/mail/show/ignore error
}

, , .

Answer 2

catch try.

echo $e- > getMessage();// ( ), db .

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