319 lines
11 KiB
PHP
319 lines
11 KiB
PHP
<?php
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// $Id$
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/**
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* @file
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* Database interface code for SQLite embedded database engine.
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*/
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/**
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* @ingroup database
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* @{
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*/
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include_once DRUPAL_ROOT . '/includes/database/prefetch.inc';
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/**
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* Specific SQLite implementation of DatabaseConnection.
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*/
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class DatabaseConnection_sqlite extends DatabaseConnection {
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public function __construct(array $connection_options = array()) {
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// We don't need a specific PDOStatement class here, we simulate it below.
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$this->statementClass = NULL;
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// This driver defaults to transaction support, except if explicitly passed FALSE.
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$this->transactionSupport = !isset($connection_options['transactions']) || $connection_options['transactions'] !== FALSE;
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parent::__construct('sqlite:' . $connection_options['database'], '', '', array(
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// Force column names to lower case.
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PDO::ATTR_CASE => PDO::CASE_LOWER,
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));
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$this->exec('PRAGMA encoding="UTF-8"');
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// Create functions needed by SQLite.
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$this->sqliteCreateFunction('if', array($this, 'sqlFunctionIf'));
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$this->sqliteCreateFunction('greatest', array($this, 'sqlFunctionGreatest'));
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$this->sqliteCreateFunction('pow', 'pow', 2);
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$this->sqliteCreateFunction('length', 'strlen', 1);
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$this->sqliteCreateFunction('md5', 'md5', 1);
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$this->sqliteCreateFunction('concat', array($this, 'sqlFunctionConcat'));
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$this->sqliteCreateFunction('substring', array($this, 'sqlFunctionSubstring'), 3);
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$this->sqliteCreateFunction('substring_index', array($this, 'sqlFunctionSubstringIndex'), 3);
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$this->sqliteCreateFunction('rand', array($this, 'sqlFunctionRand'));
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}
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/**
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* SQLite compatibility implementation for the IF() SQL function.
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*/
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public function sqlFunctionIf($condition, $expr1, $expr2 = NULL) {
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return $condition ? $expr1 : $expr2;
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}
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/**
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* SQLite compatibility implementation for the GREATEST() SQL function.
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*/
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public function sqlFunctionGreatest() {
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$args = func_get_args();
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foreach ($args as $k => $v) {
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if (is_null($v)) {
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unset($args);
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}
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}
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if (count($args)) {
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return max($args);
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}
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else {
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return NULL;
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}
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}
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/**
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* SQLite compatibility implementation for the CONCAT() SQL function.
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*/
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public function sqlFunctionConcat() {
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$args = func_get_args();
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return implode('', $args);
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}
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/**
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* SQLite compatibility implementation for the SUBSTRING() SQL function.
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*/
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public function sqlFunctionSubstring($string, $from, $length) {
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return substr($string, $from - 1, $length);
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}
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/**
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* SQLite compatibility implementation for the SUBSTRING_INDEX() SQL function.
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*/
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public function sqlFunctionSubstringIndex($string, $delimiter, $count) {
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$end = 0;
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for ($i = 0; $i < $count; $i++) {
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$end = strpos($string, $delimiter, $end + 1);
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if ($end === FALSE) {
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$end = strlen($string);
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}
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}
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return substr($string, 0, $end);
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}
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/**
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* SQLite compatibility implementation for the RAND() SQL function.
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*/
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public function sqlFunctionRand($seed = NULL) {
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if (isset($seed)) {
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mt_srand($seed);
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}
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return mt_rand() / mt_getrandmax();
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}
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/**
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* SQLite-specific implementation of DatabaseConnection::prepare().
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*
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* We don't use prepared statements at all at this stage. We just create
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* a DatabaseStatement_sqlite object, that will create a PDOStatement
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* using the semi-private PDOPrepare() method below.
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*/
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public function prepare($query, $options = array()) {
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return new DatabaseStatement_sqlite($this, $query, $options);
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}
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/**
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* NEVER CALL THIS FUNCTION: YOU MIGHT DEADLOCK YOUR PHP PROCESS.
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*
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* This is a wrapper around the parent PDO::prepare method. However, as
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* the PDO SQLite driver only closes SELECT statements when the PDOStatement
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* destructor is called and SQLite does not allow data change (INSERT,
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* UPDATE etc) on a table which has open SELECT statements, you should never
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* call this function and keep a PDOStatement object alive as that can lead
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* to a deadlock. This really, really should be private, but as
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* DatabaseStatement_sqlite needs to call it, we have no other choice but to
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* expose this function to the world.
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*/
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public function PDOPrepare($query, array $options = array()) {
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return parent::prepare($query, $options);
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}
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public function queryRange($query, $from, $count, array $args = array(), array $options = array()) {
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return $this->query($query . ' LIMIT ' . $from . ', ' . $count, $args, $options);
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}
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public function queryTemporary($query, array $args = array(), array $options = array()) {
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$tablename = $this->generateTemporaryTableName();
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$this->query(preg_replace('/^SELECT/i', 'CREATE TEMPORARY TABLE {' . $tablename . '} AS SELECT', $query), $args, $options);
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return $tablename;
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}
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public function driver() {
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return 'sqlite';
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}
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public function databaseType() {
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return 'sqlite';
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}
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public function mapConditionOperator($operator) {
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// We don't want to override any of the defaults.
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static $specials = array(
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'LIKE' => array('postfix' => " ESCAPE '\\'"),
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);
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return isset($specials[$operator]) ? $specials[$operator] : NULL;
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}
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public function prepareQuery($query, $cache = TRUE) {
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// It makes no sense to use the static prepared statement cache here,
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// because all the work in our implementation is done in
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// DatabaseStatement_sqlite::execute() and cannot be cached.
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return $this->prepare($this->prefixTables($query));
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}
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public function nextId($existing_id = 0) {
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$transaction = $this->startTransaction();
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// We can safely use literal queries here instead of the slower query
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// builder because if a given database breaks here then it can simply
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// override nextId. However, this is unlikely as we deal with short strings
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// and integers and no known databases require special handling for those
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// simple cases. If another transaction wants to write the same row, it will
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// wait until this transaction commits.
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$stmt = $this->query('UPDATE {sequences} SET value = GREATEST(value, :existing_id) + 1', array(
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':existing_id' => $existing_id,
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));
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if (!$stmt->rowCount()) {
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$this->query('INSERT INTO {sequences} (value) VALUES (:existing_id + 1)', array(
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':existing_id' => $existing_id,
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));
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}
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// The transaction gets committed when the transaction object gets destroyed
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// because it gets out of scope.
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return $new_value;
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}
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}
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/**
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* Specific SQLite implementation of DatabaseConnection.
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*
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* See DatabaseConnection_sqlite::PDOPrepare() for reasons why we must prefetch
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* the data instead of using PDOStatement.
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*
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* @see DatabaseConnection_sqlite::PDOPrepare()
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*/
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class DatabaseStatement_sqlite extends DatabaseStatementPrefetch implements Iterator, DatabaseStatementInterface {
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/**
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* SQLite specific implementation of getStatement().
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*
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* The PDO SQLite layer doesn't replace numeric placeholders in queries
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* correctly, and this makes numeric expressions (such as COUNT(*) >= :count)
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* fail. We replace numeric placeholders in the query ourselves to work
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* around this bug.
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*
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* See http://bugs.php.net/bug.php?id=45259 for more details.
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*/
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protected function getStatement($query, &$args = array()) {
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if (count($args)) {
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// Check if $args is a simple numeric array.
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if (range(0, count($args) - 1) === array_keys($args)) {
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// In that case, we have unnamed placeholders.
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$count = 0;
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$new_args = array();
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foreach ($args as $value) {
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if (is_numeric($value)) {
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$query = substr_replace($query, $value, strpos($query, '?'), 1);
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}
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else {
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$placeholder = ':db_statement_placeholder_' . $count++;
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$query = substr_replace($query, $placeholder, strpos($query, '?'), 1);
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$new_args[$placeholder] = $value;
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}
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}
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$args = $new_args;
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}
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else {
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// Else, this is using named placeholders.
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foreach ($args as $placeholder => $value) {
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if (is_numeric($value)) {
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// We will remove this placeholder from the query and PDO throws an
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// exception if the number of placeholders in the query and the
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// arguments does not match.
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unset($args[$placeholder]);
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// PDO allows placeholders to not be prefixed by a colon. See
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// http://marc.info/?l=php-internals&m=111234321827149&w=2 for
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// more.
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if ($placeholder[0] != ':') {
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$placeholder = ":$placeholder";
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}
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// When replacing the placeholders, make sure we search for the
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// exact placeholder. For example, if searching for
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// ':db_placeholder_1', do not replace ':db_placeholder_11'.
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$query = preg_replace('/' . preg_quote($placeholder) . '\b/', $value, $query);
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}
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}
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}
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}
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return $this->dbh->PDOPrepare($query);
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}
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public function execute($args = array(), $options = array()) {
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try {
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$return = parent::execute($args, $options);
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}
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catch (PDOException $e) {
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if (!empty($e->errorInfo[1]) && $e->errorInfo[1] === 17) {
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// The schema has changed. SQLite specifies that we must resend the query.
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$return = parent::execute($args, $options);
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}
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else {
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// Rethrow the exception.
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throw $e;
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}
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}
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// In some weird cases, SQLite will prefix some column names by the name
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// of the table. We post-process the data, by renaming the column names
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// using the same convention as MySQL and PostgreSQL.
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$rename_columns = array();
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foreach ($this->columnNames as $k => $column) {
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// In some SQLite versions, SELECT DISTINCT(field) will return "(field)"
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// instead of "field".
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if (preg_match("/^\((.*)\)$/", $column, $matches)) {
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$rename_columns[$column] = $matches[1];
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$this->columnNames[$k] = $matches[1];
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$column = $matches[1];
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}
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// Remove "table." prefixes.
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if (preg_match("/^.*\.(.*)$/", $column, $matches)) {
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$rename_columns[$column] = $matches[1];
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$this->columnNames[$k] = $matches[1];
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}
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}
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if ($rename_columns) {
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// DatabaseStatementPrefetch already extracted the first row,
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// put it back into the result set.
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if (isset($this->currentRow)) {
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$this->data[0] = &$this->currentRow;
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}
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// Then rename all the columns across the result set.
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foreach ($this->data as $k => $row) {
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foreach ($rename_columns as $old_column => $new_column) {
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$this->data[$k][$new_column] = $this->data[$k][$old_column];
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unset($this->data[$k][$old_column]);
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}
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}
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// Finally, extract the first row again.
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$this->currentRow = $this->data[0];
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unset($this->data[0]);
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}
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return $return;
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}
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}
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/**
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* @} End of "ingroup database".
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*/
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