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<?php
/**
* CDbSchema class file.
*
* @author Qiang Xue <qiang.xue@gmail.com>
* @link http://www.yiiframework.com/
* @copyright Copyright © 2008-2009 Yii Software LLC
* @license http://www.yiiframework.com/license/
*/
/**
* CDbSchema is the base class for retrieving metadata information.
*
* @author Qiang Xue <qiang.xue@gmail.com>
* @version $Id: CDbSchema.php 1467 2009-10-17 22:05:57Z qiang.xue $
* @package system.db.schema
* @since 1.0
*/
abstract class CDbSchema extends CComponent
{
private $_tableNames=array();
private $_tables=array();
private $_connection;
private $_builder;
private $_cacheExclude=array();
/**
* Creates a table instance representing the metadata for the named table.
* @return CDbTableSchema driver dependent table metadata, null if the table does not exist.
*/
abstract protected function createTable($name);
/**
* Constructor.
* @param CDbConnection database connection.
*/
public function __construct($conn)
{
$conn->setActive(true);
$this->_connection=$conn;
foreach($conn->schemaCachingExclude as $name)
$this->_cacheExclude[$name]=true;
}
/**
* @return CDbConnection database connection. The connection is active.
*/
public function getDbConnection()
{
return $this->_connection;
}
/**
* Obtains the metadata for the named table.
* @param string table name
* @return CDbTableSchema table metadata. Null if the named table does not exist.
*/
public function getTable($name)
{
if(isset($this->_tables[$name]))
return $this->_tables[$name];
else if(!isset($this->_cacheExclude[$name]) && ($duration=$this->_connection->schemaCachingDuration)>0 && $this->_connection->schemaCacheID!==false && ($cache=Yii::app()->getComponent($this->_connection->schemaCacheID))!==null)
{
$key='yii:dbschema'.$this->_connection->connectionString.':'.$this->_connection->username.':'.$name;
if(($table=$cache->get($key))===false)
{
$table=$this->createTable($name);
$cache->set($key,$table,$duration);
}
return $this->_tables[$name]=$table;
}
else
return $this->_tables[$name]=$this->createTable($name);
}
/**
* Returns the metadata for all tables in the database.
* @param string 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.
* Each array element is an instance of {@link CDbTableSchema} (or its child class).
* The array keys are table names.
* @since 1.0.2
*/
public function getTables($schema='')
{
$tables=array();
foreach($this->getTableNames($schema) as $name)
$tables[$name]=$this->getTable($name);
return $tables;
}
/**
* Returns all table names in the database.
* @param string the schema of the tables. Defaults to empty string, meaning the current or default schema.
* If not empty, the returned table names will be prefixed with the schema name.
* @return array all table names in the database.
* @since 1.0.2
*/
public function getTableNames($schema='')
{
if(!isset($this->_tableNames[$schema]))
$this->_tableNames[$schema]=$this->findTableNames($schema);
return $this->_tableNames[$schema];
}
/**
* @return CDbCommandBuilder the SQL command builder for this connection.
*/
public function getCommandBuilder()
{
if($this->_builder!==null)
return $this->_builder;
else
return $this->_builder=$this->createCommandBuilder();
}
/**
* Refreshes the schema.
* This method resets the loaded table metadata and command builder
* so that they can be recreated to reflect the change of schema.
*/
public function refresh()
{
if(($duration=$this->_connection->schemaCachingDuration)>0 && $this->_connection->schemaCacheID!==false && ($cache=Yii::app()->getComponent($this->_connection->schemaCacheID))!==null)
{
foreach(array_keys($this->_tables) as $name)
{
if(!isset($this->_cacheExclude[$name]))
{
$key='yii:dbschema'.$this->_connection->connectionString.':'.$this->_connection->username.':'.$name;
$cache->delete($key);
}
}
}
$this->_tables=array();
$this->_tableNames=array();
$this->_builder=null;
}
/**
* Quotes a table name for use in a query.
* @param string table name
* @return string the properly quoted table name
*/
public function quoteTableName($name)
{
return "'".$name."'";
}
/**
* Quotes a column name for use in a query.
* @param string column name
* @return string the properly quoted column name
*/
public function quoteColumnName($name)
{
return '"'.$name.'"';
}
/**
* Compares two table names.
* The table names can be either quoted or unquoted. This method
* will consider both cases.
* @param string table name 1
* @param string table name 2
* @return boolean whether the two table names refer to the same table.
*/
public function compareTableNames($name1,$name2)
{
$name1=str_replace(array('"','`',"'"),'',$name1);
$name2=str_replace(array('"','`',"'"),'',$name2);
if(($pos=strrpos($name1,'.'))!==false)
$name1=substr($name1,$pos+1);
if(($pos=strrpos($name2,'.'))!==false)
$name2=substr($name2,$pos+1);
return $name1===$name2;
}
/**
* Creates a command builder for the database.
* This method may be overridden by child classes to create a DBMS-specific command builder.
* @return CDbCommandBuilder command builder instance
*/
protected function createCommandBuilder()
{
return new CDbCommandBuilder($this);
}
/**
* Returns all table names in the database.
* This method should be overridden by child classes in order to support this feature
* because the default implemenation simply throws an exception.
* @param string the schema of the tables. Defaults to empty string, meaning the current or default schema.
* If not empty, the returned table names will be prefixed with the schema name.
* @return array all table names in the database.
* @since 1.0.2
*/
protected function findTableNames($schema='')
{
throw new CDbException(Yii::t('yii','{class} does not support fetching all table names.',
array('{class}'=>get_class($this))));
}
}