> For the complete documentation index, see [llms.txt](https://r24zeng.gitbook.io/leetcode-notebook/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://r24zeng.gitbook.io/leetcode-notebook/bu-chong-4060-dao/183.-customers-who-never-order-sql.md).

# 183. Customers Who Never Order(SQL)

\# Easy

```sql
# Write your MySQL query statement below
# is NULL的语法
select Name Customers from Customers
left join Orders on Customers.Id = Orders.CustomerId
where Orders.CustomerId is NULL;

# not in 语法
select Name Customers from Customers
where Id not in (select CustomerId from Orders);


```

{% hint style="danger" %}
不好做

**is NULL** 和 **not in** 语法很懵圈。
{% endhint %}