Detailed explanation of pdo error handling method in php

try {
$db = new pdo('mysql:host=localhost;dbname=test', $user, $pass);
$db = null;
} catch (pdoexception $ e) {
　print "error: " . $e->getmessage() . "";
die();
}
?>

Use php here 5. Object-oriented exception handling features. If there is an exception, call pdoexception to initialize an exception class.

Attribute structure of pdoexception exception class:

class pdoexception extends exception
{
public $errorinfo = null; // Error message, you can call pdo::errorinfo() or pdostatement::errorinfo() to access
protected $message ; // Exception information, you can use exception::getmessage() to access
　protected $code; // SQL status error code, you can use exception::getcode() to access
}
?>

This exception handling class is integrated with the built-in exception handling class of PHP 5. PHP 5 built-in exception handling class structure:

class exception
{
　 // Property
 protected $message = 'unknown exception'; // Exception message
 protected $code = 0; // User-defined exception code
 protected $ file; // The file name where the exception occurred
 protected $line; // The code line number where the exception occurred
 // Method
 final function getmessage(); // Return exception information
 final function getcode(); // Return exception code
　final function getfile(); // Returns the file name where the exception occurred
　final function getline(); // Returns the code line number where the exception occurred
　final function gettrace(); // backtrace() array
　final function gettraceasstring() ; // The gettrace() information that has been formatted into a string
}
?>

Correspondingly, getfile() and getline() can be appropriately called in the code to locate the error. Make debugging easier. Use process-oriented approach Code:

$db = new pdo('mysql:host=localhost;dbname=test', $user, $pass);
$rs = $db->query("select aa, bb,cc from foo");
if ($db->errorcode() != '00000'){
print_r($db->errorinfo());
exit;
}
$arr = $rs ->fetchall();
print_r($arr);
$db = null;
?>

pdo and pdostatement objects have errorcode() and errorinfo() methods, if there are no errors , errorcode() returns: 00000, otherwise some error code will be returned. errorinfo() returns an array, including error codes defined by PHP and error codes and error messages of MySQL. The array structure is as follows: array ( [0] => 42s22 [1] => 1054 [2] => unknown column 'aaa' in 'field list' ) After each query is executed, the result of errorcode() is the latest, so we can easily control the error message display ourselves. What should I do if I encounter errors again during the development of PHP and database using pdo? Treat it as above.

11.3.4 Error handling of pdo

pdo provides two methods to obtain error information in the program, one is the errorcode() method; the other is the errorinfo() method.

1. errorcode() method

The

errorcode() method is used to obtain error codes that occur when operating database handles. These error codes are called sqlstate codes. The syntax format of this method is as follows:

01 string errorcode (void) The return value of the errorcode() method is a sqlstate. sqlstate is a code composed of 5 numbers and letters.

Example of using errorcode() method:

$dsn = 'mysql:dbname=shop;host=localhost';
$user_name = 'root';
$user_psw = 'root';
$pdo = new pdo($ dsn, $user_name, $user_psw);
$pdo->exec("update mytable set age=28 where id=1 ");//The table mytable does not exist
echo "errorcode is: ".$pdo-> errorcode();
?>

The error code output is as shown below:

2. errorinfo() method

The

errorinfo() method is used to obtain error information that occurs when operating a database handle. The syntax format of this method is as follows:

01 array errorinfo (void) The return value of the errorinfo() method is an array, which contains relevant error information.

Use errorinfo() method:

$dsn = 'mysql:dbname=shop;host=localhost';
$user_name = 'root';
$user_psw = 'root';
$pdo = new pdo($ dsn, $user_name, $user_psw);
$pdo->exec("update mytable set age=28 where id=1 ");//The table mytable does not exist
echo "errorinfo is: ";
print_r($pdo ->errorinfo());
?>

, as shown below: