Fix tableExists test function for Oracle

tests/lib/dbschema.php

@@ -102,9 +102,10 @@ class Test_DBSchema extends PHPUnit_Framework_TestCase {
 				$exists = $result && $result->fetchOne();
 				break;
 			case 'oci':
-				$sql = 'SELECT table_name FROM user_tables WHERE table_name = ?';
-				$result = \OC_DB::executeAudited($sql, array($table));
-				$exists = (bool)$result->fetchOne(); //oracle uses MDB2 and returns null
+				$sql = "SELECT table_name FROM user_tables WHERE table_name = '{$table}'";
+				$query = OC_DB::prepare($sql);
+				$result = $query->execute(array());
+				$exists = $result && $result->fetchOne();
 				break;
 			case 'mssql':
 				$sql = "SELECT * FROM INFORMATION_SCHEMA.TABLES WHERE TABLE_NAME = '{$table}'";