# LeetCode 1607. Sellers With No Sales

## Description

https://leetcode.com/problems/sellers-with-no-sales/

SQL Schema

Table: `Customer`

```+---------------+---------+
| Column Name   | Type    |
+---------------+---------+
| customer_id   | int     |
| customer_name | varchar |
+---------------+---------+
customer_id is the primary key for this table.
Each row of this table contains the information of each customer in the WebStore.
```

Table: `Orders`

```+---------------+---------+
| Column Name   | Type    |
+---------------+---------+
| order_id      | int     |
| sale_date     | date    |
| order_cost    | int     |
| customer_id   | int     |
| seller_id     | int     |
+---------------+---------+
order_id is the primary key for this table.
Each row of this table contains all orders made in the webstore.
sale_date is the date when the transaction was made between the customer (customer_id) and the seller (seller_id).
```

Table: `Seller`

```+---------------+---------+
| Column Name   | Type    |
+---------------+---------+
| seller_id     | int     |
| seller_name   | varchar |
+---------------+---------+
seller_id is the primary key for this table.
Each row of this table contains the information of each seller.
```

Write an SQL query to report the names of all sellers who did not make any sales in 2020.

Return the result table ordered by `seller_name` in ascending order.

The query result format is in the following example.

````Customer` table:
+--------------+---------------+
| customer_id  | customer_name |
+--------------+---------------+
| 101          | Alice         |
| 102          | Bob           |
| 103          | Charlie       |
+--------------+---------------+

`Orders` table:
+-------------+------------+--------------+-------------+-------------+
| order_id    | sale_date  | order_cost   | customer_id | seller_id   |
+-------------+------------+--------------+-------------+-------------+
| 1           | 2020-03-01 | 1500         | 101         | 1           |
| 2           | 2020-05-25 | 2400         | 102         | 2           |
| 3           | 2019-05-25 | 800          | 101         | 3           |
| 4           | 2020-09-13 | 1000         | 103         | 2           |
| 5           | 2019-02-11 | 700          | 101         | 2           |
+-------------+------------+--------------+-------------+-------------+

`Seller` table:
+-------------+-------------+
| seller_id   | seller_name |
+-------------+-------------+
| 1           | Daniel      |
| 2           | Elizabeth   |
| 3           | Frank       |
+-------------+-------------+

Result table:
+-------------+
| `seller_name `|
+-------------+
| Frank       |
+-------------+
Daniel made 1 sale in March 2020.
Elizabeth made 2 sales in 2020 and 1 sale in 2019.
Frank made 1 sale in 2019 but no sales in 2020.```

## Explanation

First query out the seller ids where has orders in 2020 and then join the seller ids with Seller table to get seller names.

## SQL Solution

``````# Write your MySQL query statement below
SELECT seller_name from Seller a
where a.seller_id not in
(select seller_id from Orders where sale_date >= '2020-01-01' and sale_date <= '2020-12-31')
order by seller_name asc``````