Revert/optimize some changes from 48a2baf0e288accd206f5da5031d29076e130792
diff --git a/system/database/drivers/odbc/odbc_driver.php b/system/database/drivers/odbc/odbc_driver.php
index b493e93..c3735da 100644
--- a/system/database/drivers/odbc/odbc_driver.php
+++ b/system/database/drivers/odbc/odbc_driver.php
@@ -64,7 +64,7 @@
 		$this->_random_keyword = ' RND('.time().')'; // database specific random keyword
 
 		// Legacy support for DSN in the hostname field
-		if ($this->dsn === '')
+		if (empty($this->dsn))
 		{
 			$this->dsn = $this->hostname;
 		}
@@ -254,9 +254,9 @@
 	 */
 	protected function _list_tables($prefix_limit = FALSE)
 	{
-		$sql = "SHOW TABLES FROM `".$this->database."`";
+		$sql = 'SHOW TABLES FROM '.$this->database;
 
-		if ($prefix_limit !== FALSE AND $this->dbprefix !== '')
+		if ($prefix_limit !== FALSE && $this->dbprefix !== '')
 		{
 			//$sql .= " LIKE '".$this->escape_like_str($this->dbprefix)."%' ".sprintf($this->_like_escape_str, $this->_like_escape_chr);
 			return FALSE; // not currently supported