customer-who-visited-but-did-not-make-any-transactions

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Database

Table: <code>Visits</code>

<pre>
+-------------+---------+
| Column Name | Type |
+-------------+---------+
| visit_id | int |
| customer_id | int |
+-------------+---------+
visit_id is the column with unique values for this table.
This table contains information about the customers who visited the mall.
</pre>

&nbsp;

Table: <code>Transactions</code>

<pre>
+----------------+---------+
| Column Name | Type |
+----------------+---------+
| transaction_id | int |
| visit_id | int |
| amount | int |
+----------------+---------+
transaction_id is column with unique values for this table.
This table contains information about the transactions made during the visit_id.
</pre>

&nbsp;

Write a&nbsp;solution to find the IDs of the users who visited without making any transactions and the number of times they made these types of visits.

Return the result table sorted in any order.

The&nbsp;result format is in the following example.

&nbsp;
Example 1:

<pre>
Input: 
Visits
+----------+-------------+
| visit_id | customer_id |
+----------+-------------+
| 1 | 23 |
| 2 | 9 |
| 4 | 30 |
| 5 | 54 |
| 6 | 96 |
| 7 | 54 |
| 8 | 54 |
+----------+-------------+
Transactions
+----------------+----------+--------+
| transaction_id | visit_id | amount |
+----------------+----------+--------+
| 2 | 5 | 310 |
| 3 | 5 | 300 |
| 9 | 5 | 200 |
| 12 | 1 | 910 |
| 13 | 2 | 970 |
+----------------+----------+--------+
Output: 
+-------------+----------------+
| customer_id | count_no_trans |
+-------------+----------------+
| 54 | 2 |
| 30 | 1 |
| 96 | 1 |
+-------------+----------------+
Explanation: 
Customer with id = 23 visited the mall once and made one transaction during the visit with id = 12.
Customer with id = 9 visited the mall once and made one transaction during the visit with id = 13.
Customer with id = 30 visited the mall once and did not make any transactions.
Customer with id = 54 visited the mall three times. During 2 visits they did not make any transactions, and during one visit they made 3 transactions.
Customer with id = 96 visited the mall once and did not make any transactions.
As we can see, users with IDs 30 and 96 visited the mall one time without making any transactions. Also, user 54 visited the mall twice and did not make any transactions.
</pre>

find_customers

Customer Who Visited but Did Not Make Any Transactions

Sellers With No Sales

sellers-with-no-sales

没有卖出的卖家

表：<code>Visits</code>

<pre>
+-------------+---------+
| Column Name | Type |
+-------------+---------+
| visit_id | int |
| customer_id | int |
+-------------+---------+
visit_id 是该表中具有唯一值的列。
该表包含有关光临过购物中心的顾客的信息。
</pre>

&nbsp;

表：<code>Transactions</code>

<pre>
+----------------+---------+
| Column Name | Type |
+----------------+---------+
| transaction_id | int |
| visit_id | int |
| amount | int |
+----------------+---------+
transaction_id 是该表中具有唯一值的列。
此表包含 visit_id 期间进行的交易的信息。
</pre>

&nbsp;

有一些顾客可能光顾了购物中心但没有进行交易。请你编写一个解决方案，来查找这些顾客的 ID ，以及他们只光顾不交易的次数。

返回以 任何顺序 排序的结果表。

返回结果格式如下例所示。

&nbsp;

示例 1：

<pre>
<code>输入:
Visits</code>
+----------+-------------+
| visit_id | customer_id |
+----------+-------------+
| 1 | 23 |
| 2 | 9 |
| 4 | 30 |
| 5 | 54 |
| 6 | 96 |
| 7 | 54 |
| 8 | 54 |
+----------+-------------+
<code>Transactions</code>
+----------------+----------+--------+
| transaction_id | visit_id | amount |
+----------------+----------+--------+
| 2 | 5 | 310 |
| 3 | 5 | 300 |
| 9 | 5 | 200 |
| 12 | 1 | 910 |
| 13 | 2 | 970 |
+----------------+----------+--------+
输出:
+-------------+----------------+
| customer_id | count_no_trans |
+-------------+----------------+
| 54 | 2 |
| 30 | 1 |
| 96 | 1 |
+-------------+----------------+
解释:
ID = 23 的顾客曾经逛过一次购物中心，并在 ID = 12 的访问期间进行了一笔交易。
ID = 9 的顾客曾经逛过一次购物中心，并在 ID = 13 的访问期间进行了一笔交易。
ID = 30 的顾客曾经去过购物中心，并且没有进行任何交易。
ID = 54 的顾客三度造访了购物中心。在 2 次访问中，他们没有进行任何交易，在 1 次访问中，他们进行了 3 次交易。
ID = 96 的顾客曾经去过购物中心，并且没有进行任何交易。
如我们所见，ID 为 30 和 96 的顾客一次没有进行任何交易就去了购物中心。顾客 54 也两次访问了购物中心并且没有进行任何交易。</pre>