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<?php
/**
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* Driver class file.
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*
* @author Qiang Xue <qiang.xue@gmail.com>
* @link http://www.yiiframework.com/
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* @copyright Copyright &copy; 2008-2012 Yii Software LLC
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* @license http://www.yiiframework.com/license/
*/
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namespace yii\db\dao;
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use yii\db\Exception;
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/**
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* Driver is the base class for all database driver classes.
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*
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* Driver implements the DBMS-specific methods to support retrieving meta data of a database.
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*
* @property QueryBuilder $queryBuilder the query builder for this connection.
* @property array $tableNames the names of all tables in this database.
* @property array $tableSchemas the meta data for all tables in this database.
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*
* @author Qiang Xue <qiang.xue@gmail.com>
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* @since 2.0
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*/
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abstract class Driver extends \yii\base\Object
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{
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/**
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* @var Connection the database connection
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*/
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public $connection;
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/**
* @var array list of ALL table names in the database
*/
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private $_tableNames = array();
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/**
* @var array list of loaded table meta data (table name => TableSchema)
*/
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private $_tables = array();
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/**
* @var QueryBuilder the query builder for this database
*/
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private $_builder;
/**
* Loads the metadata for the specified table.
* @param string $name table name
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* @return TableSchema DBMS-dependent table metadata, null if the table does not exist.
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*/
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abstract protected function loadTableSchema($name);
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/**
* Constructor.
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* @param Connection $connection database connection.
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*/
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public function __construct($connection)
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{
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$this->connection = $connection;
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}
/**
* Obtains the metadata for the named table.
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* @param string $name table name. The table name may contain schema name if any. Do not quote the table name.
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* @param boolean $refresh whether to reload the table schema even if it is found in the cache.
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* @return TableSchema table metadata. Null if the named table does not exist.
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*/
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public function getTableSchema($name, $refresh = false)
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{
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if (isset($this->_tables[$name]) && !$refresh) {
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return $this->_tables[$name];
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}
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$db = $this->connection;
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$realName = $db->expandTablePrefix($name);
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// temporarily disable query caching
if ($db->queryCachingDuration >= 0) {
$qcDuration = $db->queryCachingDuration;
$db->queryCachingDuration = -1;
}
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if (!in_array($name, $db->schemaCachingExclude, true) && $db->schemaCachingDuration >= 0 && ($cache = \Yii::$application->getComponent($db->schemaCacheID)) !== null) {
$key = $this->getCacheKey($name);
if ($refresh || ($table = $cache->get($key)) === false) {
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$table = $this->loadTableSchema($realName);
if ($table !== null) {
$cache->set($key, $table, $db->schemaCachingDuration);
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}
}
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$this->_tables[$name] = $table;
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} else {
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$this->_tables[$name] = $table = $this->loadTableSchema($realName);
}
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if (isset($qcDuration)) { // re-enable query caching
$db->queryCachingDuration = $qcDuration;
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}
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return $table;
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}
/**
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* Returns the cache key for the specified table name.
* @param string $name the table name
* @return string the cache key
*/
public function getCacheKey($name)
{
return __CLASS__ . "/{$this->connection->dsn}/{$this->connection->username}/{$name}";
}
/**
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* Returns the metadata for all tables in the database.
* @param string $schema the schema of the tables. Defaults to empty string, meaning the current or default schema.
* @return array the metadata for all tables in the database.
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* Each array element is an instance of [[TableSchema]] (or its child class).
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*/
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public function getTableSchemas($schema = '')
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{
$tables = array();
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foreach ($this->getTableNames($schema) as $name) {
if (($table = $this->getTableSchema($name)) !== null) {
$tables[] = $table;
}
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}
return $tables;
}
/**
* Returns all table names in the database.
* @param string $schema the schema of the tables. Defaults to empty string, meaning the current or default schema.
* If not empty, the returned table names will be prefixed with the schema name.
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* @param boolean $refresh whether to fetch the latest available table names. If this is false,
* table names fetched previously (if available) will be returned.
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* @return array all table names in the database.
*/
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public function getTableNames($schema = '', $refresh = false)
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{
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if (!isset($this->_tableNames[$schema]) || $refresh) {
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$this->_tableNames[$schema] = $this->findTableNames($schema);
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}
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return $this->_tableNames[$schema];
}
/**
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* @return QueryBuilder the query builder for this connection.
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*/
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public function getQueryBuilder()
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{
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if ($this->_builder === null) {
$this->_builder = $this->createQueryBuilder();
}
return $this->_builder;
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}
/**
* Refreshes the schema.
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* This method cleans up the cached table schema and names
* so that they can be recreated to reflect the database schema change.
* @param string $tableName the name of the table that needs to be refreshed.
* If null, all currently loaded tables will be refreshed.
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*/
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public function refresh($tableName = null)
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{
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$db = $this->connection;
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if ($db->schemaCachingDuration >= 0 && ($cache = \Yii::$application->getComponent($db->schemaCacheID)) !== null) {
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if ($tableName === null) {
foreach ($this->_tables as $name => $table) {
$cache->delete($this->getCacheKey($name));
}
$this->_tables = array();
} else {
$cache->delete($this->getCacheKey($tableName));
unset($this->_tables[$tableName]);
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}
}
}
/**
* Quotes a table name for use in a query.
* If the table name contains schema prefix, the prefix will also be properly quoted.
* @param string $name table name
* @return string the properly quoted table name
* @see quoteSimpleTableName
*/
public function quoteTableName($name)
{
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if (strpos($name, '.') === false) {
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return $this->quoteSimpleTableName($name);
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}
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$parts = explode('.', $name);
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foreach ($parts as $i => $part) {
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$parts[$i] = $this->quoteSimpleTableName($part);
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}
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return implode('.', $parts);
}
/**
* Quotes a simple table name for use in a query.
* A simple table name does not schema prefix.
* @param string $name table name
* @return string the properly quoted table name
*/
public function quoteSimpleTableName($name)
{
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return strpos($name, "'") !== false ? $name : "'" . $name . "'";
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}
/**
* Quotes a column name for use in a query.
* If the column name contains prefix, the prefix will also be properly quoted.
* @param string $name column name
* @return string the properly quoted column name
* @see quoteSimpleColumnName
*/
public function quoteColumnName($name)
{
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if (($pos = strrpos($name, '.')) !== false) {
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$prefix = $this->quoteTableName(substr($name, 0, $pos)) . '.';
$name = substr($name, $pos + 1);
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} else {
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$prefix = '';
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}
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return $prefix . $this->quoteSimpleColumnName($name);
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}
/**
* Quotes a simple column name for use in a query.
* A simple column name does not contain prefix.
* @param string $name column name
* @return string the properly quoted column name
*/
public function quoteSimpleColumnName($name)
{
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return strpos($name, '"') !== false || $name === '*' ? $name : '"' . $name . '"';
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}
/**
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* Creates a query builder for the database.
* This method may be overridden by child classes to create a DBMS-specific query builder.
* @return QueryBuilder query builder instance
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*/
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public function createQueryBuilder()
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{
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return new QueryBuilder($this->connection);
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}
/**
* Returns all table names in the database.
* This method should be overridden by child classes in order to support this feature
* because the default implementation simply throws an exception.
* @param string $schema the schema of the tables. Defaults to empty string, meaning the current or default schema.
* If not empty, the returned table names will be prefixed with the schema name.
* @return array all table names in the database.
*/
protected function findTableNames($schema = '')
{
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throw new Exception(get_class($this) . 'does not support fetching all table names.');
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}
}