php - 我的插入语句有什么问题？

Question

由于某种原因，我只能从表中选择数据，但无法插入。

即函数 nee() 工作正常，但 wee() 不行......今天早些时候它工作......有人知道原因吗？

Class wtf{
    private $db;
    public function __construct(){
        $this->db = new Store_Connection();
        $this->db = $this->db->dbStore();
    }

    public function nee(){
        $st = $this->db->prepare("select paid from sales where id=14");
        $st->execute();
        $product = $st->fetch(PDO::FETCH_OBJ);
        print_r($product);
    }

    public function wee(){
        $st = $this->db->prepare("insert into sales(paid) values (sdf)");
        $st->execute();

    }

}

$work = new wtf();
$work->wee();

Answer 1

尝试这样

$st = $this->db->prepare("insert into sales(paid) values ('sdf')");