will a false returned PDO execute() the same as the exception it thrown?

问题

As requested I reformat the question:

For the following code:

$newPDO=new PDO($DSN,$USER,$PASS);
$newPDO->setAttribute(PDO::ATTR_ERRMODE,PDO::ERRMODE_EXCEPTION);
$SQL='SOME SQL STATEMENT MAYBE FAULTY';
try{
$Query=$newPDO->Prepare($SQL)
$Success=$Query->execute();
if(!$Success)
  echo('A');
}
catch(PDOException $e)
{
  echo('B');
}

Question is, is it possible to see 'A' printed? Will the answer varies for different type of $SQL like select or insert?

Original question:

First I set the attribute to PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION, so that, I think, when execute() encounters an error from the DB, it should throw an exception. Then I realized that if that's true, I may not even have to check the return of execute() as long as an exception thrown is the same as a 'false' returned. I just need to catch from outside. If nothing caught the query should be ok.
But I am not sure about this as execute() does not throw exception according to the manual by default. I tried several operations like duplicate PK and unique constraint violation when I insert something. my assertion is supported: PDO will throw an exception and I can get the detaield error msg from DB. However I don't know whether this is a universal truth. Is it possible to get a false from execute(), and no PDOEXCEPTION thrown when I have set ERRMODE to maximum? *

回答1:

Try this:

   try {
      //Initial query processing
      $execute = $query->execute()
      if (!$execute) {
        //catch the exception
        throw new Exception ("blah")
      }
    } catch (Exception $e) {
      //Exception logic here

    }

Write your queries like this & if they encounter an exception in the try section, it will relay to the catch section and you can handle it however you like (whether or not id depends on a certain case).

If there are no exceptions it will never reach the catch statement, and your query will just execute.

When it comes to DUPLICATES -> you need to work around this in SQL. For example your query could be :

INSERT INTO table (a,b,c) VALUES (1,2,3),(4,5,6) ON DUPLICATE KEY UPDATE c=VALUES(a)+VALUES(b);

回答2:

I have seen execute() returning false without throwing an exception which is kind of unexpected / bad behaviour in my opinion. This means that we basically have to do both - error and exception handling in parallel.

In my case: if I prepared an insert query without any parameters and then executed with a parameter. Execute will not throw an exception but return false. I suggest anyone to use @mlishn's solution.

来源：https://stackoverflow.com/questions/11617169/will-a-false-returned-pdo-execute-the-same-as-the-exception-it-thrown

标签

php

exception

pdo

execute