SQLite Functions (PDO_SQLITE)
简介
PDO_SQLITE is a driver that implements the PHP Data Objects (PDO) interface to enable access to SQLite 3 databases.
In PHP 5.1, the SQLite extension also provides a driver for SQLite 2 databases; while it is not technically a part of the PDO_SQLITE driver, it behaves similarly, so it is documented alongside it. The SQLite 2 driver for PDO is provided primarily to make it easier to import legacy SQLite 2 database files into an application that uses the faster, more efficient SQLite 3 driver. As a result, the SQLite 2 driver is not as feature-rich as the SQLite 3 driver.
Note:
PDO_SQLITE allows using strings apart from streams together with
PDO::PARAM_LOB.
安装
The PDO_SQLITE PDO driver is enabled by default. To disable, --without-pdo-sqlite[=DIR] may be used, where the optional [=DIR] is the sqlite base install directory.
Table of Contents
- PDO_SQLITE DSN — Connecting to SQLite databases
- PDO::sqliteCreateAggregate — Registers an aggregating User Defined Function for use in SQL statements
- PDO::sqliteCreateCollation — Registers a User Defined Function for use as a collating function in SQL statements
- PDO::sqliteCreateFunction — Registers a User Defined Function for use in SQL statements
用户评论:
[#1] tris dot php at tfconsulting dot com dot au [2014-05-15 04:34:56]
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;
}
}
?>
[#2] nospam8715 at dririan dot com [2012-11-10 21:22:43]
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.
[#3] gopal at gopalarathnam dot com [2007-03-27 02:36:30]
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
// ...
[#4] gmac63 at charter dot net [2006-08-10 07:38:18]
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 :
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!
[#5] Duffalo [2006-07-06 16:41:24]
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.
[#6] aidan at php dot net [2005-10-01 02:36:51]
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.