Error handling of PDO in PHP_PHP tutorial

Object-oriented approach
Let’s first look at the handling of connection errors, etc. The error handling of PDO in PHP is handled in an object-oriented approach:

Copy code The code is as follows:

try {
$db = new PDO('mysql:host=localhost;dbname=test', $user, $pass) ;
　$db = null;
} catch (PDOException $e) {
print "Error: " . $e->getMessage() . "
";
die();
}
?>

Here we use the object-oriented exception handling feature of PHP 5. If there is an exception, PDOException is initialized to initialize an exception class.
Attribute structure of PDOException exception class:

Copy code The code is as follows:

class PDOException extends Exception
{
public $errorInfo = null; // Error message, you can call PDO::errorInfo() or PDOStatement::errorInfo() to access
protected $message; // Exception message, You can try 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. Let’s take a brief look at the built-in exception handling class structure of PHP 5:

Copy code The code is as follows:

class Exception
{
// Attributes
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(); // Return the file name where the exception occurred
final function getLine (); // Return the code line number where the exception occurred
final function getTrace(); // backtrace() array
final function getTraceAsString(); // getTrace() information formatted into a string
}
?>

Correspondingly, getFile() and getLine() can be appropriately called in the code to locate errors and make debugging more convenient.
Use the process-oriented approach
Look at the code first:

Copy the code The code is as follows:

$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 is no error, errorCode() returns: 00000, otherwise some error code will be returned. errorInfo() returns an array, including error codes defined by PHP and MySQL error codes and error messages. 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 It's easy to control the error message display yourself.
What should I do if I encounter errors again during PHP and database development using PDO? Treat it as above.

11.3.4 PDO error handling

PDO provides two methods to obtain error information in the program, one is the errorCode() method; the other is 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. The following is an example of using the errorCode() method:

[Program 11-17] CD code11pdoerrorCode.php

Copy code Code As follows:

$dsn = 'mysql:dbname=shop;host=localhost';
$user_name = 'root';
$user_psw = ' root';
$pdo = new PDO($dsn, $user_name, $user_psw);
$pdo->exec("update mytable set age=28 where id=1 ");//table mytable
echo "errorCode is: ".$pdo->errorCode();
?>

The error code output by the above code is shown in Figure 11-13.

2. errorInfo() method

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) errorInfo() method The return value is an array, which contains relevant error information. The sample code using the errorInfo() method is as follows:

[Program 11-18] CD code11pdoerrorInfo.php

Copy code The code is as follows:

$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());
?>

The error message output by the above code is shown in Figure 11-14.

http://www.bkjia.com/PHPjc/324303.htmlwww.bkjia.comtruehttp: //www.bkjia.com/PHPjc/324303.htmlTechArticleObject-oriented approach Let’s first look at the handling of connection errors, etc., error handling of PDO in PHP, using object-oriented The way to handle it: Copy the code as follows: ?php try { $db = new PD...