你应该在 `WHERE` 子句中使用选民的身份证明来唯一标识投票者。
这可能会在你的 `PHP` 中设置为会话变量。
```sql
UPDATE user 
SET status = '已投票' 
WHERE id = $userID

// 准备并绑定
$statement = $conn->prepare("UPDATE user SET status = '已投票' WHERE id = ?");
$statement->bind_param("i", $userID);

<details>
<summary>英文:</summary>
You should use the voter&#39;s ID in the `WHERE` clause to uniquely identify who voted.  
This will likely be set in your `PHP` as a session variable.  
```sql
UPDATE user 
SET status = &#39;Voted&#39; 
WHERE id = $userID

// prepare and bind
$statement = $conn->prepare("UPDATE user SET status = 'Voted' WHERE id = ?");
$statement->bind_param("i", $userID);