+--------------+---------+
| Column Name | Type |
+--------------+---------+
| account | int |
| name | varchar |
+--------------+---------+
account 是该表的主键.
表中的每一行包含银行里中每一个用户的账号.
+---------------+---------+
| Column Name | Type |
+---------------+---------+
| trans_id | int |
| account | int |
| amount | int |
| transacted_on | date |
+---------------+---------+
trans_id 是该表主键.
该表的每一行包含了所有账户的交易改变情况.
如果用户收到了钱, 那么金额是正的; 如果用户转了钱, 那么金额是负的.
所有账户的起始余额为 0.
写一个 SQL, 报告余额高于 10000 的所有用户的名字和余额. 账户的余额等于包含该账户的所有交易的总和.
返回结果表单没有顺序要求.
查询结果格式如下例所示.
Users table:
+------------+--------------+
| account | name |
+------------+--------------+
| 900001 | Alice |
| 900002 | Bob |
| 900003 | Charlie |
+------------+--------------+
Transactions table:
+------------+------------+------------+---------------+
| trans_id | account | amount | transacted_on |
+------------+------------+------------+---------------+
| 1 | 900001 | 7000 | 2020-08-01 |
| 2 | 900001 | 7000 | 2020-09-01 |
| 3 | 900001 | -3000 | 2020-09-02 |
| 4 | 900002 | 1000 | 2020-09-12 |
| 5 | 900003 | 6000 | 2020-08-07 |
| 6 | 900003 | 6000 | 2020-09-07 |
| 7 | 900003 | -4000 | 2020-09-11 |
+------------+------------+------------+---------------+
Result table:
+------------+------------+
| name | balance |
+------------+------------+
| Alice | 11000 |
+------------+------------+
Alice 的余额为(7000 + 7000 - 3000) = 11000.
Bob 的余额为1000.
Charlie 的余额为(6000 + 6000 - 4000) = 8000.
select name, sum(amount) balance
from Users join Transactions using(account)
group by account
having balance >10000