大家好，我是空空star，本篇带大家了解一道简单的力扣sql练习题。

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前言

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一、题目：1587. 银行账户概要 II

表: Users

+--------------+---------+
| 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.

表: Transactions

+---------------+---------+
| 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.

二、解题

1.正确示范①

提交SQL

select name,sum(amount) balance
from Users u1
join Transactions u2
on u1.account=u2.account
group by u1.account
having sum(amount)>10000;

运行结果

2.正确示范②

提交SQL

select name,balance from(
    select name,sum(amount) balance
    from Users u1
    join Transactions u2
    on u1.account=u2.account
    group by u1.account
) u where balance>10000;

运行结果

3.正确示范③

提交SQL

select name,balance from(
    select name,sum(amount) balance
    from Users u1,Transactions u2
    where u1.account=u2.account
    group by u1.account
) u where balance>10000;

运行结果

4.正确示范④

提交SQL

select name,sum(amount) balance
from Users u1,Transactions u2
where u1.account=u2.account
group by u1.account
having sum(amount)>10000;

运行结果

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