pg_last_error

(PHP 4 >= 4.2.0, PHP 5, PHP 7, PHP 8)

pg_last_error — Obtiene una cadena con el último mensaje de error de la conexión

Descripción

pg_last_error(resource $connection = ?): string

pg_last_error() devuelve el último mensaje de error para una connection determinada.

Los mensajes de error pueden ser sobrescritos por las llamadas de función internas de PostgreSQL (libpq). Puede no devolver un mensaje de error apropiado si se producen varios errores dentro de una función de módulo PostgreSQL.

Use pg_result_error(), pg_result_error_field(), pg_result_status() y pg_connection_status() Para un mejor manejo de errores.

Nota:
Esta función se llamaba pg_errormessage().

Parámetros

connection: Recurso de conexión de base de datos PostgreSQL. Cuando connection no esta presente, la conexión por defecto es usada. La conexión por defecto es la ultima conexión hecha por pg_connect() o pg_pconnect().

Valores devueltos

Un string que contiene el último mensaje de error dado por connection, o false en caso de error.

Ejemplos

Ejemplo #1 Ejemplo depg_last_error()

<?php
  $dbconn = pg_connect("dbname=publisher") or die("Could not connect");

  // Consulta que falla
  $res = pg_query($dbconn, "select * from doesnotexist");
  
  echo pg_last_error($dbconn);
?>

Ver también

pg_result_error() - Get error message associated with result
pg_result_error_field() - Returns an individual field of an error report

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User Contributed Notes 1 note

down

Tamas Bolner ¶

14 years ago

From a practical view there are two types of error messages when using transactions:

-"Normal" errors: in this case, the application should stop the current process and show an error message to the user.

-Deadlock errors. This shows that the deadlock detection process of PostgreSQL found a circle of dependency, and broke it by rolling back the transaction in one of the processes, which gets this error msg. In this case, the application should not stop, but repeat the transaction.

I found no discrete way to find out which case are we dealing with. This interface doesn't support error codes, so we have to search for patterns in the message text.

Here is an example for PostgreSQL database connection class. It throws a PostgresException on "normal" errors, and DependencyException in the case of a broken deadlock, when we have to repeat the transaction.

postgres.php:
<?php
class PostgresException extends Exception {
    function __construct($msg) { parent::__construct($msg); }
}

class DependencyException extends PostgresException {
    function __construct() { parent::__construct("deadlock"); }
}

class pg {
    public static $connection;
    
    private static function connect() {
        self::$connection = @pg_connect("dbname=foodb user=foouser password=foopasswd");
        if (self::$connection === FALSE) {
            throw(new PostgresException("Can't connect to database server."));
        }
    }
    
    public static function query($sql) {
        if (!isset(self::$connection)) {
            self::connect();
        }
        
        $result = @pg_query(self::$connection, $sql);
        if ($result === FALSE) {
            $error = pg_last_error(self::$connection);
            if (stripos($error, "deadlock detected") !== false) throw(new DependencyException());
            
            throw(new PostgresException($error.": ".$sql));
        }
        
        $out = array();
        while ( ($d = pg_fetch_assoc($result)) !== FALSE) {
            $out[] = $d;
        }
        
        return $out;
    }
}
?>

It should be used in this way:

test.php:
<?php
include("postgres.php");

do {
    $repeat = false;
    try {
        pg::query("begin");
        
        ...

        $result = pg::query("SELECT * FROM public.kitten");

        ...

        pg::query("commit");
    }
    catch (DependencyException $e) {
        pg::query("rollback");
        $repeat = true;
    }
} while ($repeat);
?>

The normal errors should be caught at the frontend.

Tamas

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