minor bugs fix

README.md

@@ -118,17 +118,21 @@ $rows = $response->fetchAll();
 
 ```php
 $batchRequest = new Cassandra\Request\Batch();
-$batchRequest->appendQueryId($preparedData['id'], $strictValues)
-	->appendQuery(
-		'INSERT INTO "students" ("id", "name", "age") VALUES (:id, :name, :age)',
-		[
-			'id' => new Cassandra\Type\Uuid('c5420d81-499e-4c9c-ac0c-fa6ba3ebc2bc'),
-			'name' => new Cassandra\Type\Varchar('Mark'),
-			'age' => 20,
-		]
-	);
-
-$response = $connection->syncRequest($batch);
+
+// Append a prepared query
+$batchRequest->appendQueryId($preparedData['id'], $strictValues);
+
+// Append a query string
+$batchRequest->appendQuery(
+	'INSERT INTO "students" ("id", "name", "age") VALUES (:id, :name, :age)',
+	[
+		'id' => new Cassandra\Type\Uuid('c5420d81-499e-4c9c-ac0c-fa6ba3ebc2bc'),
+		'name' => new Cassandra\Type\Varchar('Mark'),
+		'age' => 20,
+	]
+);
+
+$response = $connection->syncRequest($batchRequest);
 $rows = $response->fetchAll();
 ```
 

src/Request/Batch.php

@@ -40,7 +40,7 @@ class Batch extends Request{
 	 * @param array $options
 	 */
 	public function __construct($type = null, $consistency = null, $options = []) {
-		$this->_batchType = $type ?: Batch::TYPE_LOGGED;
+		$this->_batchType = $type === null ? Batch::TYPE_LOGGED : $type;
 		$this->_consistency = $consistency === null ? Request::CONSISTENCY_QUORUM : $consistency;
 		$this->_options = $options;
 	}

src/Response/Result.php

@@ -326,7 +326,7 @@ public function fetchCol($index = 0){
 		$array = new \SplFixedArray($rowCount);
 
 		for($i = 0; $i < $rowCount; ++$i){
-			foreach($columns as $j => $column){
+			foreach($this->_metadata['columns'] as $j => $column){
 				$value = $this->_readBytesAndConvertToType($column['type']);
 
 				if ($j == $index)