diff --git a/framework/db/dao/ColumnSchema.php b/framework/db/dao/ColumnSchema.php
index 807a6dd..b614039 100644
--- a/framework/db/dao/ColumnSchema.php
+++ b/framework/db/dao/ColumnSchema.php
@@ -11,7 +11,7 @@
 namespace yii\db\dao;
 
 /**
- * ColumnSchema class describes the meta data of a column in a database table.
+ * ColumnSchema class describes the metadata of a column in a database table.
  *
  * @author Qiang Xue <qiang.xue@gmail.com>
  * @since 2.0
diff --git a/framework/db/dao/Connection.php b/framework/db/dao/Connection.php
index 14f3953..7c1b19b 100644
--- a/framework/db/dao/Connection.php
+++ b/framework/db/dao/Connection.php
@@ -464,7 +464,7 @@ class Connection extends \yii\base\ApplicationComponent
 			if (isset($this->driverMap[$driver])) {
 				return $this->_driver = \Yii::createObject($this->driverMap[$driver], $this);
 			} else {
-				throw new Exception("Connection does not support reading meta data for '$driver' database.");
+				throw new Exception("Connection does not support reading metadata for '$driver' database.");
 			}
 		}
 	}
diff --git a/framework/db/dao/Driver.php b/framework/db/dao/Driver.php
index e183749..3437868 100644
--- a/framework/db/dao/Driver.php
+++ b/framework/db/dao/Driver.php
@@ -15,11 +15,11 @@ use yii\db\Exception;
 /**
  * Driver is the base class for all database driver classes.
  *
- * Driver implements the DBMS-specific methods to support retrieving meta data of a database.
+ * Driver implements the DBMS-specific methods to support retrieving metadata of a database.
  *
  * @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.
+ * @property array $tableSchemas the metadata for all tables in this database.
  *
  * @author Qiang Xue <qiang.xue@gmail.com>
  * @since 2.0
@@ -54,7 +54,7 @@ abstract class Driver extends \yii\base\Object
 	 */
 	private $_tableNames = array();
 	/**
-	 * @var array list of loaded table meta data (table name => TableSchema)
+	 * @var array list of loaded table metadata (table name => TableSchema)
 	 */
 	private $_tables = array();
 	/**
diff --git a/framework/db/dao/TableSchema.php b/framework/db/dao/TableSchema.php
index 777bdda..1ed2420 100644
--- a/framework/db/dao/TableSchema.php
+++ b/framework/db/dao/TableSchema.php
@@ -11,7 +11,7 @@
 namespace yii\db\dao;
 
 /**
- * TableSchema represents the meta data of a database table.
+ * TableSchema represents the metadata of a database table.
  *
  * @property array $columnNames list of column names
  *
diff --git a/framework/db/dao/mysql/Driver.php b/framework/db/dao/mysql/Driver.php
index b995e88..3a77236 100644
--- a/framework/db/dao/mysql/Driver.php
+++ b/framework/db/dao/mysql/Driver.php
@@ -14,7 +14,7 @@ use yii\db\dao\TableSchema;
 use yii\db\dao\ColumnSchema;
 
 /**
- * Driver is the class for retrieving meta data from a MySQL database (version 4.1.x and 5.x).
+ * Driver is the class for retrieving metadata from a MySQL database (version 4.1.x and 5.x).
  *
  * @author Qiang Xue <qiang.xue@gmail.com>
  * @since 2.0
@@ -24,7 +24,7 @@ class Driver extends \yii\db\dao\Driver
 	/**
 	 * @var array mapping from physical column types (keys) to abstract column types (values)
 	 */
-	public $typeMap = array( // dbType => type
+	public $typeMap = array(
 		'tinyint' => self::TYPE_SMALLINT,
 		'bit' => self::TYPE_SMALLINT,
 		'smallint' => self::TYPE_SMALLINT,
@@ -75,6 +75,16 @@ class Driver extends \yii\db\dao\Driver
 	}
 
 	/**
+	 * 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
+	 */
+	public function createQueryBuilder()
+	{
+		return new QueryBuilder($this->connection);
+	}
+
+	/**
 	 * Loads the metadata for the specified table.
 	 * @param string $name table name
 	 * @return \yii\db\dao\TableSchema driver dependent table metadata. Null if the table does not exist.
@@ -91,9 +101,9 @@ class Driver extends \yii\db\dao\Driver
 	}
 
 	/**
-	 * Generates various kinds of table names.
-	 * @param \yii\db\dao\TableSchema $table the table instance
-	 * @param string $name the unquoted table name
+	 * Resolves the table name and schema name (if any).
+	 * @param \yii\db\dao\TableSchema $table the table metadata object
+	 * @param string $name the table name
 	 */
 	protected function resolveTableNames($table, $name)
 	{
@@ -127,16 +137,17 @@ class Driver extends \yii\db\dao\Driver
 		$this->resolveColumnType($c);
 		$c->resolvePhpType();
 
-		$this->resolveDefaultValue($c, $column['Default']);
+		$this->resolveColumnDefault($c, $column['Default']);
 
 		return $c;
 	}
 
 	/**
-	 * @param \yii\db\dao\ColumnSchema $column
-	 * @param string $value
+	 * Resolves the default value for the column.
+	 * @param \yii\db\dao\ColumnSchema $column the column metadata object
+	 * @param string $value the default value fetched from database
 	 */
-	protected function resolveDefaultValue($column, $value)
+	protected function resolveColumnDefault($column, $value)
 	{
 		if ($column->type !== 'timestamp' || $value !== 'CURRENT_TIMESTAMP') {
 			$column->defaultValue = $column->typecast($value);
@@ -144,8 +155,8 @@ class Driver extends \yii\db\dao\Driver
 	}
 
 	/**
-	 * Extracts the PHP type from DB type.
-	 * @param \yii\db\dao\ColumnSchema $column the column
+	 * Resolves the abstract data type for the column.
+	 * @param \yii\db\dao\ColumnSchema $column the column metadata object
 	 */
 	public function resolveColumnType($column)
 	{
@@ -186,7 +197,7 @@ class Driver extends \yii\db\dao\Driver
 	}
 
 	/**
-	 * Collects the table column metadata.
+	 * Collects the metadata of table columns.
 	 * @param \yii\db\dao\TableSchema $table the table metadata
 	 * @return boolean whether the table exists in the database
 	 */
@@ -195,21 +206,21 @@ class Driver extends \yii\db\dao\Driver
 		$sql = 'SHOW COLUMNS FROM ' . $table->quotedName;
 		try {
 			$columns = $this->connection->createCommand($sql)->queryAll();
-		}
-		catch (\Exception $e) {
+		} catch (\Exception $e) {
 			return false;
 		}
 		foreach ($columns as $column) {
-			$table->columns[$c->name] = $c = $this->createColumn($column);
-			if ($c->isPrimaryKey) {
+			$column = $this->createColumn($column);
+			$table->columns[$column->name] = $column;
+			if ($column->isPrimaryKey) {
 				if ($table->primaryKey === null) {
-					$table->primaryKey = $c->name;
+					$table->primaryKey = $column->name;
 				} elseif (is_string($table->primaryKey)) {
-					$table->primaryKey = array($table->primaryKey, $c->name);
+					$table->primaryKey = array($table->primaryKey, $column->name);
 				} else {
-					$table->primaryKey[] = $c->name;
+					$table->primaryKey[] = $column->name;
 				}
-				if ($c->autoIncrement) {
+				if ($column->autoIncrement) {
 					$table->sequenceName = '';
 				}
 			}
@@ -224,20 +235,23 @@ class Driver extends \yii\db\dao\Driver
 	protected function findConstraints($table)
 	{
 		$row = $this->connection->createCommand('SHOW CREATE TABLE ' . $table->quotedName)->queryRow();
-		$matches = array();
+		if (isset($row['Create Table'])) {
+			$sql = $row['Create Table'];
+		} else {
+			$row = array_values($row);
+			$sql = $row[1];
+		}
+
 		$regexp = '/FOREIGN KEY\s+\(([^\)]+)\)\s+REFERENCES\s+([^\(^\s]+)\s*\(([^\)]+)\)/mi';
-		foreach ($row as $sql) {
-			if (preg_match_all($regexp, $sql, $matches, PREG_SET_ORDER)) {
-				foreach ($matches as $match) {
-					$fks = array_map('trim', explode(',', str_replace('`', '', $match[1])));
-					$pks = array_map('trim', explode(',', str_replace('`', '', $match[3])));
-					$constraint = array(str_replace('`', '', $match[2]));
-					foreach ($fks as $k => $name) {
-						$constraint[$name] = $pks[$k];
-					}
-					$table->foreignKeys[] = $constraint;
+		if (preg_match_all($regexp, $sql, $matches, PREG_SET_ORDER)) {
+			foreach ($matches as $match) {
+				$fks = array_map('trim', explode(',', str_replace('`', '', $match[1])));
+				$pks = array_map('trim', explode(',', str_replace('`', '', $match[3])));
+				$constraint = array(str_replace('`', '', $match[2]));
+				foreach ($fks as $k => $name) {
+					$constraint[$name] = $pks[$k];
 				}
-				break;
+				$table->foreignKeys[] = $constraint;
 			}
 		}
 	}
@@ -255,19 +269,9 @@ class Driver extends \yii\db\dao\Driver
 		}
 		$sql = 'SHOW TABLES FROM ' . $this->quoteSimpleTableName($schema);
 		$names = $this->connection->createCommand($sql)->queryColumn();
-		foreach ($names as &$name) {
-			$name = $schema . '.' . $name;
+		foreach ($names as $i => $name) {
+			$names[$i] = $schema . '.' . $name;
 		}
 		return $names;
 	}
-
-	/**
-	 * Creates a query builder for the database.
-	 * This method may be overridden by child classes to create a DBMS-specific query builder.
-	 * @return QueryBuilder query builder instance
-	 */
-	public function createQueryBuilder()
-	{
-		return new QueryBuilder($this->connection);
-	}
 }
diff --git a/framework/db/dao/mysql/QueryBuilder.php b/framework/db/dao/mysql/QueryBuilder.php
index 5f5934c..d1a46bf 100644
--- a/framework/db/dao/mysql/QueryBuilder.php
+++ b/framework/db/dao/mysql/QueryBuilder.php
@@ -10,6 +10,8 @@
 
 namespace yii\db\dao\mysql;
 
+use yii\db\Exception;
+
 /**
  * QueryBuilder builds a SQL statement based on the specification given as a [[Query]] object.
  *
@@ -42,16 +44,17 @@ class QueryBuilder extends \yii\db\dao\QueryBuilder
 	/**
 	 * Builds a SQL statement for renaming a column.
 	 * @param string $table the table whose column is to be renamed. The name will be properly quoted by the method.
-	 * @param string $name the old name of the column. The name will be properly quoted by the method.
+	 * @param string $oldName the old name of the column. The name will be properly quoted by the method.
 	 * @param string $newName the new name of the column. The name will be properly quoted by the method.
 	 * @return string the SQL statement for renaming a DB column.
 	 */
-	public function renameColumn($table, $name, $newName)
+	public function renameColumn($table, $oldName, $newName)
 	{
 		$quotedTable = $this->driver->quoteTableName($table);
 		$row = $this->connection->createCommand('SHOW CREATE TABLE ' . $quotedTable)->queryRow();
-		if ($row === false)
-			throw new CDbException(Yii::t('yii', 'Unable to find "{column}" in table "{table}".', array('{column}' => $name, '{table}' => $table)));
+		if ($row === false) {
+			throw new Exception("Unable to find '$oldName' in table '$table'.");
+		}
 		if (isset($row['Create Table'])) {
 			$sql = $row['Create Table'];
 		} else {
@@ -60,14 +63,14 @@ class QueryBuilder extends \yii\db\dao\QueryBuilder
 		}
 		if (preg_match_all('/^\s*`(.*?)`\s+(.*?),?$/m', $sql, $matches)) {
 			foreach ($matches[1] as $i => $c) {
-				if ($c === $name) {
-					return "ALTER TABLE $quotedTable CHANGE " . $this->driver->quoteColumnName($name)
+				if ($c === $oldName) {
+					return "ALTER TABLE $quotedTable CHANGE " . $this->driver->quoteColumnName($oldName)
 						. ' ' . $this->driver->quoteColumnName($newName) . ' ' . $matches[2][$i];
 				}
 			}
 		}
 		// try to give back a SQL anyway
-		return "ALTER TABLE $quotedTable CHANGE " . $this->driver->quoteColumnName($name) . ' ' . $newName;
+		return "ALTER TABLE $quotedTable CHANGE " . $this->driver->quoteColumnName($oldName) . ' ' . $newName;
 	}
 
 	/**