Funciones de SQLite (PDO_SQLITE)

Introducción

PDO_SQLITE es un controlador que implementa la interfaz Objetos de Datos de PHP (PDO, siglas en inglés de PHP Data Objects) para habilitar el acceso a bases de datos de SQLite 3.

En PHP 5.1, la extensión SQLite también proporciona un controlador para bases de datos de SQLite 2; aunque no es técnicamente una parte del controlador PDO_SQLITE, se comporta de manera similar, por lo que está documentado codo con codo. El controlador SQLite 2 para PDO es proporcionado pricipalmente para hacer más la importación de ficheros de bases de datos atiguos de SQLite a una aplicación que utilice el controlador SQLite 3 más rápido y más eficiente. Como consecuencia, el controlador SQLite 2 no tiene unas características tan ricas como el controlador SQLite 3.

Nota:

PDO_SQLITE permite usar cadenas aparte de flujos junto con PDO::PARAM_LOB.

Instalación

El controlador PDO_SQLITE PDO está habilitado por omisión. Para deshabilitarlo, se puede usar --without-pdo-sqlite[=DIR] , donde el parámetro opcional [=DIR] es el directorio base de instalación de sqlite.

Tabla de contenidos

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User Contributed Notes 6 notes

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0
nospam8715 at dririan dot com
2 years ago
Instead of compiling an old version of SQLite to create a database using an older database format that the version of SQLite bundled with PDO can handle, you can (much more easily) just run the query "PRAGMA legacy_file_format = TRUE;" BEFORE creating the database (if you have an existing database, run ".dump" from the sqlite shell on your database, run the sqlite shell on a new database, run the PRAGMA, then paste the contents of the .dump). That will ensure SQLite creates a database readable by SQLite 3.0 and later.
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gopal at gopalarathnam dot com
7 years ago
If you get an error reporting "invalid resource" when trying to query the database table and looping through it, the version of the SQLite extension compiled in to PHP might be incompatible with the version that had created the database (like SQLite 2.x vs 3.x).

The database open itself might be successful, failing only when querying.

$dbh = new PDO('sqlite:/tmp/foo.db'); // success
foreach ($dbh->query('SELECT * FROM bar') as $row) // prints invalid resource
    // ...
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Duffalo
8 years ago
Note that as of the date of this post, PDO_SQLITE will not interact with database files created with the current version of the SQLite console application, sqlite-3.3.6.

It is currently necessary to obtain version 3.2.8, available from http://www.sqlite.org/ but only by entering the URI manually, as there is no link. Go to http://www.sqlite.org/download.html and find the URI of the version you're looking for, then make the appropriate version number substitution.
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aidan at php dot net
9 years ago
If you receive an error while trying to write to a sqlite database (update, delete, drop):

Warning: PDO::query() [function.query]: SQLSTATE[HY000]: General error: 1 unable to open database

The folder that houses the database file must be writeable.
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tris dot php at tfconsulting dot com dot au
6 months ago
After wrestling with "General error: 5 database is locked" errors for a highly concurrent project I finally wrapped the PDO transaction code with a semaphore.  No errors since...

Obviously only works if all processes use the subclass and wrap database modifying statements in beginTransaction() .. commit().  The same could be achieved with flock() if semaphore is not available on your system but will be slower.

<?php
class SQLitePDO extends PDO {
    function
__construct($filename) {
       
$filename = realpath($filename);
       
parent::__construct('sqlite:' . $filename);

       
$key = ftok($filename, 'a');
       
$this->sem = sem_get($key);
    }

    function
beginTransaction() {
       
sem_acquire($this->sem);
        return
parent::beginTransaction();
    }

    function
commit() {
       
$success = parent::commit();
       
sem_release($this->sem);
        return
$success;
    }

    function
rollBack() {
       
$success = parent::rollBack();
       
sem_release($this->sem);
        return
$success;
    }
}
?>
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gmac63 at charter dot net
8 years ago
Issue:
Error: SQLSTATE[HY000]: General error: 1 unsupported file format

Resolution:
To solve this (and/or many issues) involving this type of error, I assumed the error to be generated from php. Well, it was to an extent. The sqlite pdo code offered the solution:

I researched the error by grep'ing the php source code and found the error string to come from php-5.1.4/ext/pdo_sqlite/sqlite/src/prepare.c, lines 265:278 :

/*
** file_format==1    Version 3.0.0.
** file_format==2    Version 3.1.3.
** file_format==3    Version 3.1.4.
**
** Version 3.0 can only use files with file_format==1. Version 3.1.3
** can read and write files with file_format==1 or file_format==2.
** Version 3.1.4 can read and write file formats 1, 2 and 3.
*/
if( meta[1]>3 ){
   sqlite3BtreeCloseCursor(curMain);
   sqlite3SetString(pzErrMsg, "unsupported file format", (char*)0);
   return SQLITE_ERROR;
}

This is interesting as I am running SQLite version 3.3.5 which the databases were created in. I see that the SQLite PDO source in the php source is :
      # cat ext/pdo_sqlite/sqlite/VERSION
       3.2.8

My solution was then to find a version of sqlite that was =< 3.1.4. I found source for 3.1.3, compiled, recreated my database using that version (NOTE: the databases are unsupported between 3.1.x and 3.2.x versions of SQLite). Once I did this it worked.

Also as a side note, to get SQLite compiled as a PDO, I had to:

1) configure with
...
--enable-pdo=shared \
--with-sqlite=shared \
--with-pdo-sqlite=shared
--with-zlib
... \
'make && make install' if configure is successful.

2) Make sure the pdo libs were copied/installed to the correct directory. On my installation it was /usr/local/include/php/ext/pdo/

3) Make these changes in my php.ini:
  - change ' extension_dir = "./" ' to ' extension_dir="/usr/local/include/php/ext/pdo/" '
  - add/edit in this order:
      extension=pdo.so
      extension=pdo_sqlite.so
      extension=sqlite.so

4) test php with : 'php -m' at the command line and solve any issues from there. Mostly php.ini config issues. Also restart the http service!
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