php - Reference - frequently asked questions about PDO -


what this?

this list of asked questions regarding php data objects

why this?

as pdo has features unknown regular php user, questions regarding prepared statements , error handling in pdo quite frequent. so, place them can found.

what should here?

if question has been closevoted list, please find question below , apply fix code. idea take brief other questions, make prepared other common pitfalls.

the list

see also

pdo query fails can't see errors. how error message pdo?

to able see database errors, 1 have set pdo errmode exceptions. exceptions better regular errors in many ways: contains stack trace, can caught using try..catch or handled using dedicated error handler. , unhandled, act regular php errors providing important information, following site-wide error reporting settings.

note setting mode connection option let pdo throw exceptions on connection errors too, important.
so, here example creating pdo connection right way:

$dsn = "mysql:host=$host;dbname=$db;charset=utf8"; $opt = array(     pdo::attr_errmode            => pdo::errmode_exception,     // other options  ); $pdo = new pdo($dsn, $user, $pass, $opt);

connecting way, notified of database errors, occurred during query execution. note have able see php errors in general. on live site have peek error logs, so, settings have be

error_reporting(e_all); ini_set('display_errors',0); ini_set('log_errors',1);

while on local development server it's ok make errors on screen:

error_reporting(e_all); ini_set('display_errors',1);

and of course should never ever use error suppression operator (@) in front of pdo statements.

also, due many bad examples telling wrap every pdo statement try..catch block, have make distinct note:

do not use try..catch operator echo error message. uncaught exception excellent purpose, act same way other php errors - so, can define behavior using site-wide settings - so, you have error message without useless code. while unconditionally echoed error message may reveal sensitive information potential attacker, yet confuse honest visitor.

  • a custom exception handler added later, not required. new users, recommended use unhandled exceptions, extremely informative, helpful , secure.
  • use try..catch if going handle error - say, rollback transaction.

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