Почему срабатывает Warning: SQLite3::exec(): near "(": syntax error по последней строке кода?

<?php
require "INewsDB.class.php";
class NewsDB implements INewsDB{
const DB_NAME = "../news.db";
const ERR_PROPERTY = "Wrong property name";
private $_db;
function __construct(){
    $this->_db = new SQLite3(self::DB_NAME);
    if(!filesize(self::DB_NAME)){
        $sql = "CREATE TABLE msgs(
            id INTEGER PRIMARY KEY AUTOINCREMENT,
            title TEXT,
            category INTEGER,
            description TEXT,
            source TEXT,
            datetime INTEGER
        )";
        $this->_db->exec($sql) or die($this->_db->lastErrorMsg());
        $sql = "CREATE TABLE category(
            id INTEGER,
            name TEXT
        )";
        $this->_db->exec($sql) or die($this->_db->lastErrorMsg());
        $sql = "INSERT INTO category(id, name)
        SELECT 1 as id, 'Политика' as name
        UNION SELECT 2 as id, 'Культура' as name
        UNION SELECT 3 as id, 'Спорт' as name ";
        $this->_db->exec($sql) or die($this->_db->lastErrorMsg());
    }
}
function __destruct(){
    unset($this->_db);
}
function __get($name){
    if($name == "db")
        return $this->_db;
        throw new Exeption(self::ERR_PROPERTY);
}
function __set($name, $value){
    throw new Exeption(self::ERR_PROPERTY);
}
function saveNews($title, $category, $description, $source){
    $dt = time();
    $sql = "INSERT INTO (title, category, description, source, datetime)
            VALUES('$title', $category, '$description', '$source', $dt)";
   return $this->_db->exec($sql);
}
}