/classes/fSchema.php

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<?php
/**
 * Gets schema information for the selected database
 * 
 * @copyright  Copyright (c) 2007-2012 Will Bond
 * @author     Will Bond [wb] <will@flourishlib.com>
 * @license    http://flourishlib.com/license
 * 
 * @package    Flourish
 * @link       http://flourishlib.com/fSchema
 * 
 * @version    1.0.0b51
 * @changes    1.0.0b51  Fixed handling of getting tables in table creation order when a table references itself, fixed default value detection for the last column in a MySQL table [wb, 2012-01-12]
 * @changes    1.0.0b50  Fixed detection of explicitly named SQLite foreign key constraints [wb, 2011-08-23]
 * @changes    1.0.0b49  Added support for spatial/geometric data types in MySQL and PostgreSQL [wb, 2011-05-26]
 * @changes    1.0.0b48  Fixed a bug with ::getTables() not working on MySQL 4.x, fixed ::getKeys() to always return a reset array [wb, 2011-05-24]
 * @changes    1.0.0b47  Backwards Compatibility Break - ::getTables(), ::getColumnInfo(), ::getDatabases(), ::getKeys() and ::getRelationships() now return database, schema, table and column names in lowercase, added the `$creation_order` parameter to ::getTables(), fixed bugs with getting column and key information from MSSQL, Oracle and SQLite [wb, 2011-05-09]
 * @changes    1.0.0b46  Enhanced SQLite schema detection to cover situations where `UNIQUE` constraints are defined separately from the table and when comments are used in `CREATE TABLE` statements [wb, 2011-02-06]
 * @changes    1.0.0b45  Fixed Oracle auto incrementing detection to work with `INSERT OR UPDATE` triggers, fixed detection of dynamic default date/time/timestamp values for DB2 and Oracle [wb, 2010-12-04]
 * @changes    1.0.0b44  Fixed the list of valid elements for ::getColumnInfo() [wb, 2010-11-28]
 * @changes    1.0.0b43  Added the `comment` element to the information returned by ::getColumnInfo() [wb, 2010-11-28]
 * @changes    1.0.0b42  Fixed a bug with MySQL detecting default `ON DELETE` clauses [wb, 2010-10-19]
 * @changes    1.0.0b41  Fixed handling MySQL table names that require quoting [wb, 2010-08-24]
 * @changes    1.0.0b40  Fixed bugs in the documentation and error message of ::getColumnInfo() about what are valid elements [wb, 2010-07-21]
 * @changes    1.0.0b39  Fixed a regression where key detection SQL was not compatible with PostgreSQL 8.1 [wb, 2010-04-13]
 * @changes    1.0.0b38  Added Oracle support to ::getDatabases() [wb, 2010-04-13]
 * @changes    1.0.0b37  Fixed ::getDatabases() for MSSQL [wb, 2010-04-09]
 * @changes    1.0.0b36  Fixed PostgreSQL to properly report explicit `NULL` default values via ::getColumnInfo() [wb, 2010-03-30]
 * @changes    1.0.0b35  Added `max_length` values for various text and blob data types across all databases [wb, 2010-03-29]
 * @changes    1.0.0b34  Added `min_value` and `max_value` attributes to ::getColumnInfo() to specify the valid range for numeric columns [wb, 2010-03-16]
 * @changes    1.0.0b33  Changed it so that PostgreSQL unique indexes containing functions are ignored since they can't be properly detected at this point [wb, 2010-03-14]
 * @changes    1.0.0b32  Fixed ::getTables() to not include views for MySQL [wb, 2010-03-14]
 * @changes    1.0.0b31  Fixed the creation of the default caching key for ::enableCaching() [wb, 2010-03-02]
 * @changes    1.0.0b30  Fixed the class to work with lower privilege Oracle accounts and added detection of Oracle number columns [wb, 2010-01-25]
 * @changes    1.0.0b29  Added on_delete and on_update elements to one-to-one relationship info retrieved by ::getRelationships() [wb, 2009-12-16]
 * @changes    1.0.0b28  Fixed a bug with detecting some multi-column unique constraints in SQL Server databases [wb, 2009-11-13]
 * @changes    1.0.0b27  Added a parameter to ::enableCaching() to provide a key token that will allow cached values to be shared between multiple databases with the same schema [wb, 2009-10-28]
 * @changes    1.0.0b26  Added the placeholder element to the output of ::getColumnInfo(), added support for PostgreSQL, MSSQL and Oracle "schemas", added support for parsing quoted SQLite identifiers [wb, 2009-10-22]
 * @changes    1.0.0b25  One-to-one relationships utilizing the primary key as a foreign key are now properly detected [wb, 2009-09-22]
 * @changes    1.0.0b24  Fixed MSSQL support to work with ODBC database connections [wb, 2009-09-18]
 * @changes    1.0.0b23  Fixed a bug where one-to-one relationships were being listed as many-to-one [wb, 2009-07-21]
 * @changes    1.0.0b22  PostgreSQL UNIQUE constraints that are created as indexes and not table constraints are now properly detected [wb, 2009-07-08]
 * @changes    1.0.0b21  Added support for the UUID data type in PostgreSQL [wb, 2009-06-18]
 * @changes    1.0.0b20  Add caching of merged info, improved performance of ::getColumnInfo() [wb, 2009-06-15]
 * @changes    1.0.0b19  Fixed a couple of bugs with ::setKeysOverride() [wb, 2009-06-04]
 * @changes    1.0.0b18  Added missing support for MySQL mediumint columns [wb, 2009-05-18]
 * @changes    1.0.0b17  Fixed a bug with ::clearCache() not properly reseting the tables and databases list [wb, 2009-05-13]
 * @changes    1.0.0b16  Backwards Compatibility Break - ::setCacheFile() changed to ::enableCaching() and now requires an fCache object, ::flushInfo() renamed to ::clearCache(), added Oracle support [wb, 2009-05-04]
 * @changes    1.0.0b15  Added support for the three different types of identifier quoting in SQLite [wb, 2009-03-28]
 * @changes    1.0.0b14  Added support for MySQL column definitions containing the COLLATE keyword [wb, 2009-03-28]
 * @changes    1.0.0b13  Fixed a bug with detecting PostgreSQL columns having both a CHECK constraint and a UNIQUE constraint [wb, 2009-02-27]
 * @changes    1.0.0b12  Fixed detection of multi-column primary keys in MySQL [wb, 2009-02-27]
 * @changes    1.0.0b11  Fixed an issue parsing MySQL tables with comments [wb, 2009-02-25]
 * @changes    1.0.0b10  Added the ::getDatabases() method [wb, 2009-02-24]
 * @changes    1.0.0b9   Now detects unsigned and zerofill MySQL data types that do not have a parenthetical part [wb, 2009-02-16]
 * @changes    1.0.0b8   Mapped the MySQL data type `'set'` to `'varchar'`, however valid values are not implemented yet [wb, 2009-02-01]
 * @changes    1.0.0b7   Fixed a bug with detecting MySQL timestamp columns [wb, 2009-01-28]
 * @changes    1.0.0b6   Fixed a bug with detecting MySQL columns that accept `NULL` [wb, 2009-01-19]
 * @changes    1.0.0b5   ::setColumnInfo(): fixed a bug with not grabbing the real database schema first, made general improvements [wb, 2009-01-19]
 * @changes    1.0.0b4   Added support for MySQL binary data types, numeric data type options unsigned and zerofill, and per-column character set definitions [wb, 2009-01-17]
 * @changes    1.0.0b3   Fixed detection of the data type of MySQL timestamp columns, added support for dynamic default date/time values [wb, 2009-01-11]
 * @changes    1.0.0b2   Fixed a bug with detecting multi-column unique keys in MySQL [wb, 2009-01-03]
 * @changes    1.0.0b    The initial implementation [wb, 2007-09-25]
 */
class fSchema
{
	/**
	 * The place to cache to
	 * 
	 * @var fCache
	 */
	private $cache = NULL;
	
	/**
	 * The cache prefix to use for cache entries
	 * 
	 * @var string
	 */
	private $cache_prefix;
	
	/**
	 * The cached column info
	 * 
	 * @var array
	 */
	private $column_info = array();
	
	/**
	 * The column info to override
	 * 
	 * @var array
	 */
	private $column_info_override = array();
	
	/**
	 * A reference to an instance of the fDatabase class
	 * 
	 * @var fDatabase
	 */
	private $database = NULL;
	
	/**
	 * The databases on the current database server
	 * 
	 * @var array
	 */
	private $databases = NULL;
	
	/**
	 * The cached key info
	 * 
	 * @var array
	 */
	private $keys = array();
	
	/**
	 * The key info to override
	 * 
	 * @var array
	 */
	private $keys_override = array();
	
	/**
	 * The merged column info
	 * 
	 * @var array
	 */
	private $merged_column_info = array();
	
	/**
	 * The merged key info
	 * 
	 * @var array
	 */
	private $merged_keys = array();
	
	/**
	 * The relationships in the database
	 * 
	 * @var array
	 */
	private $relationships = array();
	
	/**
	 * The tables in the database
	 * 
	 * @var array
	 */
	private $tables = NULL;
	
	
	/**
	 * Sets the database
	 * 
	 * @param  fDatabase $database  The fDatabase instance
	 * @return fSchema
	 */
	public function __construct($database)
	{
		$this->database = $database;
	}
	
	
	/**
	 * All requests that hit this method should be requests for callbacks
	 * 
	 * @internal
	 * 
	 * @param  string $method  The method to create a callback for
	 * @return callback  The callback for the method requested
	 */
	public function __get($method)
	{
		return array($this, $method);		
	}
	
	
	/**
	 * Checks to see if a column is part of a single-column `UNIQUE` key
	 * 
	 * @param  string $table   The table the column is located in
	 * @param  string $column  The column to check
	 * @return boolean  If the column is part of a single-column unique key
	 */
	private function checkForSingleColumnUniqueKey($table, $column)
	{        
		foreach ($this->merged_keys[$table]['unique'] as $key) {
			if (array($column) == $key) {
				return TRUE;
			}
		}
		if (array($column) == $this->merged_keys[$table]['primary']) {
			return TRUE;
		}
		return FALSE;
	}
	
	
	/**
	 * Clears all of the schema info out of the object and, if set, the fCache object
	 * 
	 * @internal
	 * 
	 * @return void
	 */
	public function clearCache()
	{
		$this->column_info        = array();
		$this->databases          = NULL;
		$this->keys               = array();
		$this->merged_column_info = array();
		$this->merged_keys        = array();
		$this->relationships      = array();
		$this->tables             = NULL;
		if ($this->cache) {
			$prefix = $this->makeCachePrefix();
			$this->cache->delete($prefix . 'column_info');
			$this->cache->delete($prefix . 'databases');
			$this->cache->delete($prefix . 'keys');
			$this->cache->delete($prefix . 'merged_column_info');
			$this->cache->delete($prefix . 'merged_keys');
			$this->cache->delete($prefix . 'relationships');
			$this->cache->delete($prefix . 'tables');
		}
	}
	
	
	/**
	 * Returns an ordered array of table names, in a valid table creation order
	 * 
	 * @param string  $filter_table  The only return this table and tables that rely on it
	 * @return array  An array of table names
	 */
	private function determineTableCreationOrder($filter_table=NULL)
	{
		$found          = array();
		$ignored_found  = array();
		
		$current_tables = $this->getTables();
		// Prevent an infinite loop
		$last_tables    = array();
		while ($current_tables && $current_tables != $last_tables) {
			$remaining_tables = array();
			foreach ($current_tables as $table) {
				$foreign_keys = $this->getKeys($table, 'foreign');
				if (!$foreign_keys) {
					if ($filter_table !== NULL) {
						if ($table == $filter_table) {
							$found[] = $table;
						} else {
							$ignored_found[] = $table;
						}
					} else {
						$found[] = $table;
					}
					
				} else {
					$all_dependencies_met = TRUE;
					$found_dependencies   = 0;
					foreach ($foreign_keys as $foreign_key) {
						if ($table != $foreign_key['foreign_table'] && !in_array($foreign_key['foreign_table'], $found) && !in_array($foreign_key['foreign_table'], $ignored_found)) {
							$all_dependencies_met = FALSE;
							break;
						} elseif (in_array($foreign_key['foreign_table'], $found)) {
							$found_dependencies++;
						}
					}
					if ($all_dependencies_met) {
						if ($filter_table !== NULL) {
							if ($found_dependencies || $table == $filter_table) {
								$found[] = $table;
							} else {
								$ignored_found[] = $table;
							}
						} else {
							$found[] = $table;
						}
						
					} else {
						$remaining_tables[] = $table;
					}
				}
			}
			$last_tables    = $current_tables;
			$current_tables = $remaining_tables;
		}
		
		return $found;
	}
	
	
	/**
	 * Sets the schema to be cached to the fCache object specified
	 * 
	 * @param  fCache $cache      The cache to cache to
	 * @param  string $key_token  Internal use only! (this will be used in the cache key to uniquely identify the cache for this fSchema object) 
	 * @return void
	 */
	public function enableCaching($cache, $key_token=NULL)
	{
		$this->cache = $cache;
		
		if ($key_token !== NULL) {
			$this->cache_prefix = 'fSchema::' . $this->database->getType() . '::' . $key_token . '::';
		}
		$prefix = $this->makeCachePrefix();
		
		$this->column_info        = $this->cache->get($prefix . 'column_info',          array());
		$this->databases          = $this->cache->get($prefix . 'databases',            NULL);
		$this->keys               = $this->cache->get($prefix . 'keys',                 array());
		
		if (!$this->column_info_override && !$this->keys_override) {
			$this->merged_column_info = $this->cache->get($prefix . 'merged_column_info',   array());
			$this->merged_keys        = $this->cache->get($prefix . 'merged_keys',          array());  
			$this->relationships      = $this->cache->get($prefix . 'relationships',        array());
		}
		
		$this->tables             = $this->cache->get($prefix . 'tables',               NULL);   
	}
	
	
	/**
	 * Gets the column info from the database for later access
	 * 
	 * @param  string $table  The table to fetch the column info for
	 * @return void
	 */
	private function fetchColumnInfo($table)
	{
		if (isset($this->column_info[$table])) {
			return;	
		}
		
		switch ($this->database->getType()) {
			case 'db2':
				$column_info = $this->fetchDB2ColumnInfo($table);
				break;
			
			case 'mssql':
				$column_info = $this->fetchMSSQLColumnInfo($table);
				break;
			
			case 'mysql':
				$column_info = $this->fetchMySQLColumnInfo($table);
				break;
				
			case 'oracle':
				$column_info = $this->fetchOracleColumnInfo($table);
				break;
			
			case 'postgresql':
				$column_info = $this->fetchPostgreSQLColumnInfo($table);
				break;
				
			case 'sqlite':
				$column_info = $this->fetchSQLiteColumnInfo($table);
				break;
		}
			
		if (!$column_info) {
			return;	
		}
			
		$this->column_info[$table] = $column_info;
		if ($this->cache) {
			$this->cache->set($this->makeCachePrefix() . 'column_info', $this->column_info);	
		}
	}
	
	
	/**
	 * Gets the column info from a DB2 database
	 * 
	 * @param  string $table  The table to fetch the column info for
	 * @return array  The column info for the table specified - see ::getColumnInfo() for details
	 */
	private function fetchDB2ColumnInfo($table)
	{
		$column_info = array();
		
		$schema = strtolower($this->database->getUsername());
		if (strpos($table, '.') !== FALSE) {
			list ($schema, $table) = explode('.', $table);
		}
		
		$data_type_mapping = array(
			'smallint'          => 'integer',
			'integer'           => 'integer',
			'bigint'            => 'integer',
			'timestamp'         => 'timestamp',
			'date'              => 'date',
			'time'              => 'time',
			'varchar'           => 'varchar',
			'long varchar'      => 'varchar',
			'vargraphic'        => 'varchar',
			'long vargraphic'   => 'varchar',
			'character'         => 'char',
			'graphic'           => 'char',
			'real'              => 'float',
			'decimal'           => 'float',
			'numeric'           => 'float',
			'blob'              => 'blob',
			'clob'              => 'text',
			'dbclob'            => 'text'
		);
		
		$max_min_values = array(
			'smallint'   => array('min' => new fNumber(-32768),                  'max' => new fNumber(32767)),
			'integer'    => array('min' => new fNumber(-2147483648),             'max' => new fNumber(2147483647)),
			'bigint'     => array('min' => new fNumber('-9223372036854775808'),  'max' => new fNumber('9223372036854775807'))
		);
		
		// Get the column info
		$sql = "SELECT
					LOWER(C.COLNAME) AS \"COLUMN\",
					C.TYPENAME AS TYPE,
					C.NULLS AS NULLABLE,
					C.DEFAULT,
					C.LENGTH AS MAX_LENGTH,
					C.SCALE,
					CASE WHEN C.IDENTITY = 'Y' AND (C.GENERATED = 'D' OR C.GENERATED = 'A') THEN '1' ELSE '0' END AS AUTO_INCREMENT,
					CH.TEXT AS \"CONSTRAINT\",
					C.REMARKS AS \"COMMENT\"
				FROM
					SYSCAT.COLUMNS AS C LEFT JOIN
					SYSCAT.COLCHECKS AS CC ON
						C.TABSCHEMA = CC.TABSCHEMA AND
						C.TABNAME = CC.TABNAME AND
						C.COLNAME = CC.COLNAME AND
						CC.USAGE = 'R' LEFT JOIN
					SYSCAT.CHECKS AS CH ON
						C.TABSCHEMA = CH.TABSCHEMA AND
						C.TABNAME = CH.TABNAME AND
						CH.TYPE = 'C' AND
						CH.CONSTNAME = CC.CONSTNAME
				WHERE
					LOWER(C.TABSCHEMA) = %s AND
					LOWER(C.TABNAME) = %s
				ORDER BY
					C.COLNO ASC";
		
		$result = $this->database->query($sql, strtolower($schema), strtolower($table));
		
		foreach ($result as $row) {
			
			$info = array();
			
			foreach ($data_type_mapping as $data_type => $mapped_data_type) {
				if (stripos($row['type'], $data_type) === 0) {
					if (isset($max_min_values[$data_type])) {
						$info['min_value'] = $max_min_values[$data_type]['min'];
						$info['max_value'] = $max_min_values[$data_type]['max'];
					}
					$info['type'] = $mapped_data_type;
					break;
				}
			}
			
			// Handle decimal places and min/max for numeric/decimals
			if (in_array(strtolower($row['type']), array('decimal', 'numeric'))) {
				$info['decimal_places'] = $row['scale'];
				$before_digits = str_pad('', $row['max_length'] - $row['scale'], '9');
				$after_digits  = str_pad('', $row['scale'], '9');
				$max_min       = $before_digits . ($after_digits ? '.' : '') . $after_digits;
				$info['min_value'] = new fNumber('-' . $max_min);
				$info['max_value'] = new fNumber($max_min);
			}
			
			if (!isset($info['type'])) {
				$info['type'] = $row['type'];
			}
			
			// Handle the special data for varchar columns
			if (in_array($info['type'], array('char', 'varchar', 'text', 'blob'))) {
				$info['max_length'] = $row['max_length'];
			}
			
			// The generally accepted practice for boolean on DB2 is a CHAR(1) with a CHECK constraint
			if ($info['type'] == 'char' && $info['max_length'] == 1 && !empty($row['constraint'])) {
				if (is_resource($row['constraint'])) {
					$row['constraint'] = stream_get_contents($row['constraint']);
				}
				if (preg_match('/^\s*"?' . preg_quote($row['column'], '/') . '"?\s+in\s+\(\s*(\'0\',\s*\'1\'|\'1\',\s*\'0\')\s*\)\s*$/i', $row['constraint'])) {
					$info['type'] = 'boolean';
					$info['max_length'] = NULL;
				}
			}
			
			// If the column has a constraint, look for valid values
			if (in_array($info['type'], array('char', 'varchar')) && !empty($row['constraint'])) {
				if (preg_match('/^\s*"?' . preg_quote($row['column'], '/') . '"?\s+in\s+\((.*?)\)\s*$/i', $row['constraint'], $match)) {
					if (preg_match_all("/(?<!')'((''|[^']+)*)'/", $match[1], $matches, PREG_PATTERN_ORDER)) {
						$info['valid_values'] = str_replace("''", "'", $matches[1]);
					}			
				}
			}
			
			// Handle auto increment
			if ($row['auto_increment']) {
				$info['auto_increment'] = TRUE;
			}
			
			// Handle default values
			if ($row['default'] !== NULL) {
				if ($row['default'] == 'NULL') {
					$info['default'] = NULL;
				} elseif (in_array($info['type'], array('timestamp', 'date', 'time')) && $row['default'][0] != "'") {
					$info['default'] = str_replace(' ', '_', $row['default']);
				} elseif (in_array($info['type'], array('char', 'varchar', 'text', 'timestamp', 'date', 'time')) ) {
					$info['default'] = substr($row['default'], 1, -1);
				} elseif ($info['type'] == 'boolean') {
					$info['default'] = (boolean) substr($row['default'], 1, -1);
				} else {
					$info['default'] = $row['default'];
				}
			}
			
			// Handle not null
			$info['not_null'] = ($row['nullable'] == 'N') ? TRUE : FALSE;
			
			$info['comment'] = $row['comment'];
			
			$column_info[$row['column']] = $info;
		}
		
		return $column_info;
	}
	
	
	/**
	 * Fetches the key info for a DB2 database
	 * 
	 * @return array  The keys arrays for every table in the database - see ::getKeys() for details
	 */
	private function fetchDB2Keys()
	{
		$keys = array();
		
		$default_schema = strtolower($this->database->getUsername());
		
		$tables = $this->getTables();
		foreach ($tables as $table) {
			$keys[$table] = array();
			$keys[$table]['primary'] = array();
			$keys[$table]['unique']  = array();
			$keys[$table]['foreign'] = array();
		}
		
		$params  = array();
		
		$sql  = "(SELECT
					LOWER(RTRIM(R.TABSCHEMA)) AS \"SCHEMA\",
					LOWER(R.TABNAME) AS \"TABLE\",
					R.CONSTNAME AS CONSTRAINT_NAME,
					'foreign' AS \"TYPE\",
					LOWER(K.COLNAME) AS \"COLUMN\",
					LOWER(RTRIM(R.REFTABSCHEMA)) AS FOREIGN_SCHEMA,
					LOWER(R.REFTABNAME) AS FOREIGN_TABLE,
					LOWER(FK.COLNAME) AS FOREIGN_COLUMN,
					CASE R.DELETERULE WHEN 'C' THEN 'cascade' WHEN 'A' THEN 'no_action' WHEN 'R' THEN 'restrict' ELSE 'set_null' END AS ON_DELETE,
					CASE R.UPDATERULE WHEN 'A' THEN 'no_action' WHEN 'R' THEN 'restrict' END AS ON_UPDATE,
					K.COLSEQ
				FROM
					SYSCAT.REFERENCES AS R INNER JOIN 
					SYSCAT.KEYCOLUSE AS K ON
						R.CONSTNAME = K.CONSTNAME AND
						R.TABSCHEMA = K.TABSCHEMA AND
						R.TABNAME = K.TABNAME INNER JOIN
					SYSCAT.KEYCOLUSE AS FK ON
						R.REFKEYNAME = FK.CONSTNAME AND
						R.REFTABSCHEMA = FK.TABSCHEMA AND
						R.REFTABNAME = FK.TABNAME
				WHERE ";
		
		$conditions = array();
		foreach ($tables as $table) {
			if (strpos($table, '.') === FALSE) {
				$table = $default_schema . '.' . $table;
			}	
			list ($schema, $table) = explode('.', strtolower($table));
			$conditions[] = "LOWER(R.TABSCHEMA) = %s AND LOWER(R.TABNAME) = %s";
			$params[] = $schema;
			$params[] = $table;
		}
		$sql .= '((' . join(') OR( ', $conditions) . '))';
		 
		$sql .= "
				) UNION (
				SELECT
					LOWER(RTRIM(I.TABSCHEMA)) AS \"SCHEMA\",
					LOWER(I.TABNAME) AS \"TABLE\",
					LOWER(I.INDNAME) AS CONSTRAINT_NAME,
					CASE I.UNIQUERULE WHEN 'U' THEN 'unique' ELSE 'primary' END AS \"TYPE\",
					LOWER(C.COLNAME) AS \"COLUMN\",
					NULL AS FOREIGN_SCHEMA,
					NULL AS FOREIGN_TABLE,
					NULL AS FOREIGN_COLUMN,
					NULL AS ON_DELETE,
					NULL AS ON_UPDATE,
					C.COLSEQ
				FROM
					SYSCAT.INDEXES AS I INNER JOIN
					SYSCAT.INDEXCOLUSE AS C ON I.INDSCHEMA = C.INDSCHEMA AND I.INDNAME = C.INDNAME
				WHERE
					I.UNIQUERULE IN ('U', 'P') AND
					";
		
		$conditions = array();
		foreach ($tables as $table) {
			if (strpos($table, '.') === FALSE) {
				$table = $default_schema . '.' . $table;
			}	
			list ($schema, $table) = explode('.', strtolower($table));
			$conditions[] = "LOWER(I.TABSCHEMA) = %s AND LOWER(I.TABNAME) = %s";
			$params[] = $schema;
			$params[] = $table;
		}
		$sql .= '((' . join(') OR( ', $conditions) . '))';
		
		$sql .= "
				 )
				 ORDER BY 4, 1, 2, 3, 11";
		
		$result = $this->database->query($sql, $params);
		
		$last_name  = '';
		$last_table = '';
		$last_type  = '';
		foreach ($result as $row) {
			
			if ($row['constraint_name'] != $last_name) {
				
				if ($last_name) {
					if ($last_type == 'foreign' || $last_type == 'unique') {
						$keys[$last_table][$last_type][] = $temp;
					} else {
						$keys[$last_table][$last_type] = $temp;
					}
				}
				
				$temp = array();
				if ($row['type'] == 'foreign') {
					
					$temp['column']         = $row['column'];
					$temp['foreign_table']  = $row['foreign_table'];
					if ($row['foreign_schema'] != $default_schema) {
						$temp['foreign_table'] = $row['foreign_schema'] . '.' . $temp['foreign_table'];
					}
					$temp['foreign_column'] = $row['foreign_column'];
					$temp['on_delete']      = 'no_action';
					$temp['on_update']      = 'no_action';
					
					if (!empty($row['on_delete'])) {
						$temp['on_delete'] = $row['on_delete'];
					}
					if (!empty($row['on_update'])) {
						$temp['on_update'] = $row['on_update'];
					}
					
				} else {
					$temp[] = $row['column'];
				}
				
				$last_table = $row['table'];
				if ($row['schema'] != $default_schema) {
					$last_table = $row['schema'] . '.' . $last_table;
				}
				$last_name  = $row['constraint_name'];
				$last_type  = $row['type'];
				
			} else {
				$temp[] = $row['column'];
			}
		}
		
		if (isset($temp)) {
			if ($last_type == 'foreign' || $last_type == 'unique') {
				$keys[$last_table][$last_type][] = $temp;
			} else {
				$keys[$last_table][$last_type] = $temp;
			}
		}
		
		return $keys;
	}
	
	
	/**
	 * Gets the `PRIMARY KEY`, `FOREIGN KEY` and `UNIQUE` key constraints from the database
	 * 
	 * @return void
	 */
	private function fetchKeys()
	{
		if ($this->keys) {
			return;	
		}
		
		switch ($this->database->getType()) {
			case 'db2':
				$keys = $this->fetchDB2Keys();
				break;
			
			case 'mssql':
				$keys = $this->fetchMSSQLKeys();
				break;
				
			case 'mysql':
				$keys = $this->fetchMySQLKeys();
				break;
				
			case 'oracle':
				$keys = $this->fetchOracleKeys();
				break;
			
			case 'postgresql':
				$keys = $this->fetchPostgreSQLKeys();
				break;
			
			case 'sqlite':
				$keys = $this->fetchSQLiteKeys();
				break;
		}
		
		$this->keys = $keys;
		if ($this->cache) {
			$this->cache->set($this->makeCachePrefix() . 'keys', $this->keys);	
		}
	}
	
	
	/**
	 * Gets the column info from a MSSQL database
	 * 
	 * @param  string $table  The table to fetch the column info for
	 * @return array  The column info for the table specified - see ::getColumnInfo() for details
	 */
	private function fetchMSSQLColumnInfo($table)
	{
		$column_info = array();
		
		$schema = 'dbo';
		if (strpos($table, '.') !== FALSE) {
			list ($schema, $table) = explode('.', $table);
		}
		
		$data_type_mapping = array(
			'bit'               => 'boolean',
			'tinyint'           => 'integer',
			'smallint'          => 'integer',
			'int'               => 'integer',
			'bigint'            => 'integer',
			'timestamp'         => 'integer',
			'datetime'          => 'timestamp',
			'smalldatetime'     => 'timestamp',
			'datetime2'         => 'timestamp',
			'date'              => 'date',
			'time'              => 'time',
			'varchar'           => 'varchar',
			'nvarchar'          => 'varchar',
			'uniqueidentifier'  => 'varchar',
			'char'              => 'char',
			'nchar'             => 'char',
			'real'              => 'float',
			'float'             => 'float',
			'money'             => 'float',
			'smallmoney'        => 'float',
			'decimal'           => 'float',
			'numeric'           => 'float',
			'binary'            => 'blob',
			'varbinary'         => 'blob',
			'image'             => 'blob',
			'text'              => 'text',
			'ntext'             => 'text',
			'xml'               => 'text'
		);
		
		$max_min_values = array(
			'tinyint'    => array('min' => new fNumber(0),                       'max' => new fNumber(255)),
			'smallint'   => array('min' => new fNumber(-32768),                  'max' => new fNumber(32767)),
			'int'        => array('min' => new fNumber(-2147483648),             'max' => new fNumber(2147483647)),
			'bigint'     => array('min' => new fNumber('-9223372036854775808'),  'max' => new fNumber('9223372036854775807')),
			'smallmoney' => array('min' => new fNumber('-214748.3648'),          'max' => new fNumber('214748.3647')),
			'money'      => array('min' => new fNumber('-922337203685477.5808'), 'max' => new fNumber('922337203685477.5807'))
		);
		
		// Get the column info
		$sql = "SELECT
					LOWER(c.column_name)       AS 'column',
					c.data_type                AS 'type',
					c.is_nullable              AS nullable,
					c.column_default           AS 'default',
					c.character_maximum_length AS max_length,
					c.numeric_precision        AS precision,
					c.numeric_scale            AS decimal_places,
					CASE
						WHEN
							COLUMNPROPERTY(OBJECT_ID(QUOTENAME(c.table_schema) + '.' + QUOTENAME(c.table_name)), c.column_name, 'IsIdentity') = 1 AND
							OBJECTPROPERTY(OBJECT_ID(QUOTENAME(c.table_schema) + '.' + QUOTENAME(c.table_name)), 'IsMSShipped') = 0
						THEN '1'
						ELSE '0'
					END AS auto_increment,
					cc.check_clause AS 'constraint',
					CAST(ex.value AS VARCHAR(7500)) AS 'comment'
				FROM
					INFORMATION_SCHEMA.COLUMNS AS c LEFT JOIN
					INFORMATION_SCHEMA.CONSTRAINT_COLUMN_USAGE AS ccu ON
						c.column_name = ccu.column_name AND
						c.table_name = ccu.table_name AND
						c.table_catalog = ccu.table_catalog LEFT JOIN
					INFORMATION_SCHEMA.CHECK_CONSTRAINTS AS cc ON
						ccu.constraint_name = cc.constraint_name AND
						ccu.constraint_catalog = cc.constraint_catalog";
		
		if (version_compare($this->database->getVersion(), 9, '<')) {
			$sql .= " LEFT JOIN sysproperties AS ex ON ex.id = OBJECT_ID(QUOTENAME(c.table_schema) + '.' + QUOTENAME(c.table_name)) AND ex.smallid = COLUMNPROPERTY(OBJECT_ID(QUOTENAME(c.table_schema) + '.' + QUOTENAME(c.table_name)), c.column_name, 'ColumnId') AND ex.name = 'MS_Description' AND OBJECTPROPERTY(OBJECT_ID(QUOTENAME(c.table_schema) + '.' + QUOTENAME(c.table_name)), 'IsMsShipped') = 0 ";
		} else {
			$sql .= " LEFT JOIN SYS.EXTENDED_PROPERTIES AS ex ON ex.major_id = OBJECT_ID(QUOTENAME(c.table_schema) + '.' + QUOTENAME(c.table_name)) AND ex.minor_id = COLUMNPROPERTY(OBJECT_ID(QUOTENAME(c.table_schema) + '.' + QUOTENAME(c.table_name)), c.column_name, 'ColumnId') AND ex.name = 'MS_Description' AND OBJECTPROPERTY(OBJECT_ID(QUOTENAME(c.table_schema) + '.' + QUOTENAME(c.table_name)), 'IsMsShipped') = 0 ";
		}
		
		$sql .= "
					WHERE
						LOWER(c.table_name) = %s AND
						LOWER(c.table_schema) = %s AND
						c.table_catalog = DB_NAME()";
		
		$result = $this->database->query($sql, strtolower($table), strtolower($schema));
		
		foreach ($result as $row) {
			
			$info = array();
			
			foreach ($data_type_mapping as $data_type => $mapped_data_type) {
				if (stripos($row['type'], $data_type) === 0) {
					if (isset($max_min_values[$data_type])) {
						$info['min_value'] = $max_min_values[$data_type]['min'];
						$info['max_value'] = $max_min_values[$data_type]['max'];
					}
					$info['type'] = $mapped_data_type;
					break;
				}
			}
			
			// Handle decimal places and min/max for numeric/decimals
			if (in_array(strtolower($row['type']), array('decimal', 'numeric'))) {
				$info['decimal_places'] = $row['decimal_places'];
				$before_digits = str_pad('', $row['precision'] - $row['decimal_places'], '9');
				$after_digits  = str_pad('', $row['decimal_places'], '9');
				$max_min       = $before_digits . ($after_digits ? '.' : '') . $after_digits;
				$info['min_value'] = new fNumber('-' . $max_min);
				$info['max_value'] = new fNumber($max_min);
			}
			
			if (!isset($info['type'])) {
				$info['type'] = $row['type'];
			}
			
			// Handle decimal places for money/smallmoney
			if (in_array($row['type'], array('money', 'smallmoney'))) {
				$info['decimal_places'] = 2;
			}
			
			// Handle the special data for varchar columns
			if (in_array($info['type'], array('char', 'varchar', 'text', 'blob'))) {
				if ($row['type'] == 'uniqueidentifier') {
					$row['max_length'] = 32;
				} elseif ($row['max_length'] == -1) {
					$row['max_length'] = $row['type'] == 'nvarchar' ? 1073741823 : 2147483647;
				}
				$info['max_length'] = $row['max_length'];
			}
			
			// If the column has a constraint, look for valid values
			if (in_array($info['type'], array('char', 'varchar')) && !empty($row['constraint'])) {
				if (preg_match('#^\(((?:(?: OR )?\[[^\]]+\]\s*=\s*\'(?:\'\'|[^\']+)*\')+)\)$#D', $row['constraint'], $matches)) {
					$valid_values = explode(' OR ', $matches[1]);
					foreach ($valid_values as $key => $value) {
						$value = preg_replace('#^\s*\[' . preg_quote($row['column'], '#') . '\]\s*=\s*\'(.*)\'\s*$#', '\1', $value);
						$valid_values[$key] = str_replace("''", "'", $value);
					}
					// SQL Server turns CHECK constraint values into a reversed list, so we fix it here
					$info['valid_values'] = array_reverse($valid_values);
				}
			}
			
			// Handle auto increment
			if ($row['auto_increment']) {
				$info['auto_increment'] = TRUE;
			}
			
			// Handle default values
			if ($row['default'] !== NULL) {
				if ($row['default'] == '(getdate())') {
					$info['default'] = 'CURRENT_TIMESTAMP';
				} elseif (in_array($info['type'], array('char', 'varchar', 'text', 'timestamp')) ) {
					$info['default'] = substr($row['default'], 2, -2);
				} elseif ($info['type'] == 'boolean') {
					$info['default'] = (boolean) substr($row['default'], 2, -2);
				} elseif (in_array($info['type'], array('integer', 'float')) ) {
					$info['default'] = str_replace(array('(', ')'), '', $row['default']);
				} else {
					$info['default'] = pack('H*', substr($row['default'], 3, -1));
				}
			}
			
			// Handle not null
			$info['not_null'] = ($row['nullable'] == 'NO') ? TRUE : FALSE;
			
			$info['comment'] = $row['comment'];
			
			$column_info[$row['column']] = $info;
		}
		
		return $column_info;
	}
	
	
	/**
	 * Fetches the key info for an MSSQL database
	 * 
	 * @return array  The key info arrays for every table in the database - see ::getKeys() for details
	 */
	private function fetchMSSQLKeys()
	{
		$keys = array();
		
		$tables   = $this->getTables();
		foreach ($tables as $table) {
			$keys[$table] = array();
			$keys[$table]['primary'] = array();
			$keys[$table]['unique']  = array();
			$keys[$table]['foreign'] = array();
		}
		
		$sql  = "SELECT
					LOWER(c.table_schema) AS \"schema\",
					LOWER(c.table_name) AS \"table\",
					kcu.constraint_name AS constraint_name,
					CASE c.constraint_type
						WHEN 'PRIMARY KEY' THEN 'primary'
						WHEN 'FOREIGN KEY' THEN 'foreign'
						WHEN 'UNIQUE' THEN 'unique'
					END AS 'type',
					LOWER(kcu.column_name) AS 'column',
					LOWER(ccu.table_schema) AS foreign_schema,
					LOWER(ccu.table_name) AS foreign_table,
					LOWER(ccu.column_name) AS foreign_column,
					REPLACE(LOWER(rc.delete_rule), ' ', '_') AS on_delete,
					REPLACE(LOWER(rc.update_rule), ' ', '_') AS on_update
				FROM
					INFORMATION_SCHEMA.TABLE_CONSTRAINTS AS c INNER JOIN
					INFORMATION_SCHEMA.KEY_COLUMN_USAGE AS kcu ON
						c.table_name = kcu.table_name AND
						c.constraint_name = kcu.constraint_name LEFT JOIN
					INFORMATION_SCHEMA.REFERENTIAL_CONSTRAINTS AS rc ON
						c.constraint_name = rc.constraint_name LEFT JOIN
					INFORMATION_SCHEMA.CONSTRAINT_COLUMN_USAGE AS ccu ON
						ccu.constraint_name = rc.unique_constraint_name
				WHERE
					c.constraint_catalog = DB_NAME() AND
					c.table_name != 'sysdiagrams'
				ORDER BY
					LOWER(c.table_schema),
					LOWER(c.table_name),
					c.constraint_type,
					LOWER(kcu.constraint_name),
					kcu.ordinal_position,
					LOWER(kcu.column_name)";
		
		$result = $this->database->query($sql);
		
		$last_name  = '';
		$last_table = '';
		$last_type  = '';
		foreach ($result as $row) {
			
			if ($row['constraint_name'] != $last_name) {
				
				if ($last_name) {
					if ($last_type == 'foreign' || $last_type == 'unique') {
						if (!isset($keys[$last_table][$last_type])) {
							$keys[$last_table][$last_type] = array();		
						}
						$keys[$last_table][$last_type][] = $temp;
					} else {
						$keys[$last_table][$last_type] = $temp;
					}
				}
				
				$temp = array();
				if ($row['type'] == 'foreign') {
					
					$temp['column']         = $row['column'];
					$temp['foreign_table']  = $row['foreign_table'];
					if ($row['foreign_schema'] != 'dbo') {
						 $temp['foreign_table'] = $row['foreign_schema'] . '.' . $temp['foreign_table'];	
					}
					$temp['foreign_column'] = $row['foreign_column'];
					$temp['on_delete']      = 'no_action';
					$temp['on_update']      = 'no_action';
					if (!empty($row['on_delete'])) {
						$temp['on_delete'] = $row['on_delete'];
					}
					if (!empty($row['on_update'])) {
						$temp['on_update'] = $row['on_update'];
					}
					
				} else {
					$temp[] = $row['column'];
				}
				
				$last_table = $row['table'];
				if ($row['schema'] != 'dbo') {
					$last_table = $row['schema'] . '.' . $last_table;	
				}
				$last_name  = $row['constraint_name'];
				$last_type  = $row['type'];
				
			} else {
				$temp[] = $row['column'];
			}
		}
		
		if (isset($temp)) {
			if ($last_type == 'foreign' || $last_type == 'unique') {
				if (!isset($keys[$last_table][$last_type])) {
					$keys[$last_table][$last_type] = array();		
				}
				$keys[$last_table][$last_type][] = $temp;
			} else {
				$keys[$last_table][$last_type] = $temp;
			}
		}
		
		return $keys;
	}
	
	
	/**
	 * Gets the column info from a MySQL database
	 * 
	 * @param  string $table  The table to fetch the column info for
	 * @return array  The column info for the table specified - see ::getColumnInfo() for details
	 */
	private function fetchMySQLColumnInfo($table)
	{
		$data_type_mapping = array(
			'tinyint'			=> 'integer',
			'smallint'			=> 'integer',
			'mediumint'         => 'integer',
			'int'				=> 'integer',
			'bigint'			=> 'integer',
			'datetime'			=> 'timestamp',
			'timestamp'			=> 'timestamp',
			'date'				=> 'date',
			'time'				=> 'time',
			'enum'				=> 'varchar',
			'set'               => 'varchar',
			'varchar'			=> 'varchar',
			'char'				=> 'char',
			'float'				=> 'float',
			'double'			=> 'float',
			'decimal'			=> 'float',
			'binary'            => 'blob',
			'varbinary'         => 'blob',
			'tinyblob'			=> 'blob',
			'blob'				=> 'blob',
			'mediumblob'		=> 'blob',
			'longblob'			=> 'blob',
			'tinytext'			=> 'text',
			'text'				=> 'text',
			'mediumtext'		=> 'text',
			'longtext'			=> 'text',
			'geometry'          => 'blob',
			'point'             => 'blob',
			'linestring'        => 'blob',
			'polygon'           => 'blob'
		);
		
		$max_min_values = array(
			'tinyint'             => array('min' => new fNumber(-128),                    'max' => new fNumber(127)),
			'unsigned tinyint'    => array('min' => new fNumber(0),                       'max' => new fNumber(255)),
			'smallint'            => array('min' => new fNumber(-32768),                  'max' => new fNumber(32767)),
			'unsigned smallint'   => array('min' => new fNumber(0),                       'max' => new fNumber(65535)),
			'mediumint'           => array('min' => new fNumber(-8388608),                'max' => new fNumber(8388607)),
			'unsigned mediumint'  => array('min' => new fNumber(0),                       'max' => new fNumber(16777215)),
			'int'                 => array('min' => new fNumber(-2147483648),             'max' => new fNumber(2147483647)),
			'unsigned int'        => array('min' => new fNumber(0),                       'max' => new fNumber('4294967295')),
			'bigint'              => array('min' => new fNumber('-9223372036854775808'),  'max' => new fNumber('9223372036854775807')),
			'unsigned bigint'     => array('min' => new fNumber(0),                       'max' => new fNumber('18446744073709551615'))
		);
		
		$column_info = array();
		
		$result     = $this->database->query('SHOW CREATE TABLE %r', $table);
		
		try {
			$row        = $result->fetchRow();
			$create_sql = $row['Create Table'];
		} catch (fNoRowsException $e) {
			return array();
		}
		
		preg_match_all('#(?<=,|\()\s+(?:"|\`)(\w+)(?:"|\`)\s+(?:([a-z]+)(?:\(([^)]+)\))?( unsigned)?(?: zerofill)?)(?: character set [^ ]+)?(?: collate [^ ]+)?(?: NULL)?( NOT NULL)?(?: DEFAULT ((?:[^, \'\n]*|\'(?:\'\'|[^\']+)*\')))?( auto_increment)?( COMMENT \'(?:\'\'|[^\']+)*\')?( ON UPDATE CURRENT_TIMESTAMP)?\s*(?:,|\s*(?=\)))#mi', $create_sql, $matches, PREG_SET_ORDER);
		
		foreach ($matches as $match) {
			
			$info = array();
			
			foreach ($data_type_mapping as $data_type => $mapped_data_type) {
				if (stripos($match[2], $data_type) === 0) {
					if ($match[2] == 'tinyint' && $match[3] == 1) {
						$mapped_data_type = 'boolean';
					
					} elseif (preg_match('#((?:unsigned )?(?:tiny|small|medium|big)?int)#', (isset($match[4]) ? $match[4] . ' ' : '') . $data_type, $int_match)) {
						if (isset($max_min_values[$int_match[1]])) {
							$info['min_value'] = $max_min_values[$int_match[1]]['min'];
							$info['max_value'] = $max_min_values[$int_match[1]]['max'];	
						}
					}
					
					$info['type'] = $mapped_data_type;
					break;
				}
			}
			if (!isset($info['type'])) {
				$info['type'] = preg_replace('#^([a-z ]+).*$#iD', '\1', $match[2]);
			}
			
			switch ($match[2]) {
				case 'tinyblob':
				case 'tinytext':
					$info['max_length'] = 255;
					break;
				
				case 'blob':
				case 'text':
					$info['max_length'] = 65535;
					break;
				
				case 'mediumblob':
				case 'mediumtext':
					$info['max_length'] = 16777215;
					break;
				
				case 'longblob':
				case 'longtext':
					$info['max_length'] = 4294967295;
					break;
			}
		
			if (stripos($match[2], 'enum') === 0) {
				$info['valid_values'] = preg_replace("/^'|'\$/D", '', explode(",", $match[3]));
				$match[3] = 0;
				foreach ($info['valid_values'] as $valid_value) {
					if (strlen(utf8_decode($valid_value)) > $match[3]) {
						$match[3] = strlen(utf8_decode($valid_value));
					}
				}
			}
			
			// The set data type is currently only supported as a varchar
			// with a max length of all valid values concatenated by ,s
			if (stripos($match[2], 'set') === 0) {
				$values = preg_replace("/^'|'\$/D", '', explode(",", $match[3]));
				$match[3] = strlen(join(',', $values));
			}
			
			// Type specific information
			if (in_array($info['type'], array('char', 'varchar'))) {
				$info['max_length'] = $match[3];
			}
			
			// Grab the number of decimal places
			if (stripos($match[2], 'decimal') === 0) {
				if (preg_match('#^\s*(\d+)\s*,\s*(\d+)\s*$#D', $match[3], $data_type_info)) {
					$info['decimal_places'] = $data_type_info[2];
					$before_digits = str_pad('', $data_type_info[1] - $info['decimal_places'], '9');
					$after_digits  = str_pad('', $info['decimal_places'], '9');
					$max_min       = $before_digits . ($after_digits ? '.' : '') . $after_digits;
					$info['min_value'] = new fNumber('-' . $max_min);
					$info['max_value'] = new fNumber($max_min);
				}
			}
			
			// Not null
			$info['not_null'] = (!empty($match[5])) ? TRUE : FALSE;
		
			// Default values
			if (!empty($match[6]) && $match[6] != 'NULL') {
				$info['default'] = preg_replace("/^'|'\$/D", '', $match[6]);
			}
			
			if ($info['type'] == 'boolean' && isset($info['default'])) {
				$info['default'] = (boolean) $info['default'];
			}
		
			// Auto increment fields
			if (!empty($match[7])) {
				$info['auto_increment'] = TRUE;
			}
			
			// Column comments
			if (!empty($match[8])) {
				$info['comment'] = str_replace("''", "'", substr($match[8], 10, -1));
			}
		
			$column_info[strtolower($match[1])] = $info;
		}
		
		return $column_info;
	}
	
	
	/**
	 * Fetches the keys for a MySQL database
	 * 
	 * @return array  The keys arrays for every table in the database - see ::getKeys() for details
	 */
	private function fetchMySQLKeys()
	{
		$tables   = $this->getTables();
		$keys = array();
		
		foreach ($tables as $table) {
			
			$keys[$table] = array();
			$keys[$table]['primary'] = array();
			$keys[$table]['foreign'] = array();
			$keys[$table]['unique']  = array();
			
			$result = $this->database->query('SHOW CREATE TABLE %r', $table);
			$row    = $result->fetchRow();
			
			// Primary keys
			preg_match_all('/PRIMARY KEY\s+\("(.*?)"\),?\n/U', $row['Create Table'], $matches, PREG_SET_ORDER);
			if (!empty($matches)) {
				$keys[$table]['primary'] = explode('","', strtolower($matches[0][1]));
			}
			
			// Unique keys
			preg_match_all('/UNIQUE KEY\s+"([^"]+)"\s+\("(.*?)"\),?\n/U', $row['Create Table'], $matches, PREG_SET_ORDER);
			foreach ($matches as $match) {
				$keys[$table]['unique'][] = explode('","', strtolower($match[2]));
			}
			
			// Foreign keys
			preg_match_all('#FOREIGN KEY \("([^"]+)"\) REFERENCES "([^"]+)" \("([^"]+)"\)(?:\sON\sDELETE\s(SET\sNULL|SET\sDEFAULT|CASCADE|NO\sACTION|RESTRICT))?(?:\sON\sUPDATE\s(SET\sNULL|SET\sDEFAULT|CASCADE|NO\sACTION|RESTRICT))?#', $row['Create Table'], $matches, PREG_SET_ORDER);
			foreach ($matches as $match) {
				$temp = array(
					'column'         => strtolower($match[1]),
					'foreign_table'  => strtolower($match[2]),
					'foreign_column' => strtolower($match[3]),
					'on_delete'      => 'no_action',
					'on_update'      => 'no_action'
				);
				if (!empty($match[4])) {
					$temp['on_delete'] = strtolower(str_replace(' ', '_', $match[4]));
				}
				if (!empty($match[5])) {
					$temp['on_update'] = strtolower(str_replace(' ', '_', $match[5]));
				}
				$keys[$table]['foreign'][] = $temp;
			}
		}
		
		return $keys;
	}
	
	
	/**
	 * Gets the column info from an Oracle database
	 * 
	 * @param  string $table  The table to fetch the column info for
	 * @return array  The column info for the table specified - see ::getColumnInfo() for details
	 */
	private function fetchOracleColumnInfo($table)
	{
		$table = strtolower($table);
		
		$schema = strtolower($this->database->getUsername());
		if (strpos($table, '.') !== FALSE) {
			list ($schema, $table) = explode('.', $table);
		}
		
		$column_info = array();
		
		$data_type_mapping = array(
			'boolean'			=> 'boolean',
			'number'            => 'integer',
			'integer'			=> 'integer',
			'timestamp'			=> 'timestamp',
			'date'				=> 'date',
			'varchar2'          => 'varchar',
			'nvarchar2'			=> 'varchar',
			'char'              => 'char',
			'nchar'             => 'char',
			'float'				=> 'float',
			'binary_float'      => 'float',
			'binary_double'     => 'float',
			'blob'				=> 'blob',
			'bfile'             => 'varchar',
			'clob'				=> 'text',
			'nclob'             => 'text'
		);
		
		$sql = "SELECT
					LOWER(ATC.COLUMN_NAME) COLUMN_NAME,
					CASE
						WHEN
							ATC.DATA_TYPE = 'NUMBER' AND
							ATC.DATA_PRECISION IS NULL AND
							ATC.DATA_SCALE = 0
						THEN
							'integer'
						WHEN
							ATC.DATA_TYPE = 'NUMBER' AND
							ATC.DATA_PRECISION = 1 AND
							ATC.DATA_SCALE = 0
						THEN
							'boolean'
						WHEN
							ATC.DATA_TYPE = 'NUMBER' AND
							ATC.DATA_PRECISION IS NOT NULL AND
							ATC.DATA_SCALE != 0 AND
							ATC.DATA_SCALE IS NOT NULL
						THEN
							'float'
						ELSE
							LOWER(ATC.DATA_TYPE)
						END DATA_TYPE,
					CASE
						WHEN
							ATC.CHAR_LENGTH <> 0
						THEN
							ATC.CHAR_LENGTH
						WHEN
							ATC.DATA_TYPE = 'NUMBER' AND
							ATC.DATA_PRECISION != 1 AND
							ATC.DATA_SCALE != 0	AND
							ATC.DATA_PRECISION IS NOT NULL
						THEN
							ATC.DATA_SCALE
						ELSE
							NULL
						END LENGTH,
					ATC.DATA_PRECISION PRECISION,
					ATC.NULLABLE,
					ATC.DATA_DEFAULT,
					AC.SEARCH_CONDITION CHECK_CONSTRAINT,
					ACCM.COMMENTS
				FROM
					ALL_TAB_COLUMNS ATC LEFT JOIN
					ALL_CONS_COLUMNS ACC ON
						ATC.OWNER = ACC.OWNER AND
						ATC.COLUMN_NAME = ACC.COLUMN_NAME AND
						ATC.TABLE_NAME = ACC.TABLE_NAME AND
						ACC.POSITION IS NULL LEFT JOIN
					ALL_CONSTRAINTS AC ON
						AC.OWNER = ACC.OWNER AND
						AC.CONSTRAINT_NAME = ACC.CONSTRAINT_NAME AND
						AC.CONSTRAINT_TYPE = 'C' AND
						AC.STATUS = 'ENABLED' LEFT JOIN
					ALL_COL_COMMENTS ACCM ON
						ATC.OWNER = ACCM.OWNER AND
						ATC.COLUMN_NAME = ACCM.COLUMN_NAME AND
						ATC.TABLE_NAME = ACCM.TABLE_NAME
				WHERE
					LOWER(ATC.TABLE_NAME) = %s AND
					LOWER(ATC.OWNER) = %s
				ORDER BY
					ATC.TABLE_NAME ASC,
					ATC.COLUMN_ID ASC";
		
		$result = $this->database->query($sql, $table, $schema);
		
		foreach ($result as $row) {
			
			$column = $row['column_name'];
			
			// Since Oracle stores check constraints in LONG columns, it is
			// not possible to check or modify the constraints in SQL which
			// ends up causing multiple rows with duplicate data except for
			// the check constraint
			$duplicate = FALSE;
			
			if (isset($column_info[$column])) {
				$info = $column_info[$column];
				$duplicate = TRUE;
			} else {
				$info = array();
			}
			
			if (!$duplicate) {
				// Get the column type
				foreach ($data_type_mapping as $data_type => $mapped_data_type) {
					if (stripos($row['data_type'], $data_type) === 0) {
						$info['type'] = $mapped_data_type;
						break;
					}
				}
				
				if (!isset($info['type'])) {
					$info['type'] = $row['data_type'];
				}
				
				if (in_array($info['type'], array('blob', 'text'))) {
					$info['max_length'] = 4294967295;
				}
				
				if ($row['data_type'] == 'float' && $row['precision']) {
					$row['length'] = (int) $row['length'];
					$before_digits = str_pad('', $row['precision'] - $row['length'], '9');
					$after_digits  = str_pad('', $row['length'], '9');
					$max_min       = $before_digits . ($after_digits ? '.' : '') . $after_digits;
					$info['min_value'] = new fNumber('-' . $max_min);
					$info['max_value'] = new fNumber($max_min);	
				}
				
				// Handle the length of decimal/numeric fields
				if ($info['type'] == 'float' && $row['length']) {
					$info['decimal_places'] = (int) $row['length'];
				}
				
				// Handle the special data for varchar fields
				if (in_array($info['type'], array('char', 'varchar'))) {
					$info['max_length'] = (int) $row['length'];
				}
			}
			
			// Handle check constraints that are just simple lists
			if (in_array($info['type'], array('varchar', 'char')) && $row['check_constraint']) {
				if (preg_match('/^\s*"?' . preg_quote($column, '/') . '"?\s+in\s+\((.*?)\)\s*$/i', $row['check_constraint'], $match)) {
					if (preg_match_all("/(?<!')'((''|[^']+)*)'/", $match[1], $matches, PREG_PATTERN_ORDER)) {
						$info['valid_values'] = str_replace("''", "'", $matches[1]);
					}			
				} elseif (preg_match('/^\s*"?' . preg_quote($column, '/') . '"?\s*=\s*\'((\'\'|[^\']+)*)\'(\s+OR\s+"?' . preg_quote($column, '/') . '"?\s*=\s*\'((\'\'|[^\']+)*)\')*\s*$/i', $row['check_constraint'], $match)) {
					if (preg_match_all("/(?<!')'((''|[^']+)*)'/", $row['check_constraint'], $matches, PREG_PATTERN_ORDER)) {
						$info['valid_values'] = str_replace("''", "'", $matches[1]);
					}			
				}
			}
			
			if (!$duplicate) {
				// Handle default values
				if ($row['data_default'] !== NULL && trim($row['data_default']) != 'NULL') {
					if (…