[PBN笔试题]mysql 一个简单查询中的group by 和 order by 的使用

具体我忘记了，大概内容差不多如下。

两张表，内容如下：

+--------+-------+------+
| z_code | mgr   | pigs |
+--------+-------+------+
| 021    | zhang | 85   |
| 010    | wang  | 70   |
+--------+-------+------+
2 rows in set

查询最终结果

+--------+------+-------+
| z_code | city | mgr   |
+--------+------+-------+
| 010    | BJ   | wang  |
| 021    | HB   | zhang |
+--------+------+-------+
2 rows in set

A表

+------+-------+------+
| part | mgr   | pigs |
+------+-------+------+
| 001  | wang  |   20 |
| 002  | wang  |   50 |
| 011  | zhang |   49 |
| 012  | zhang |   36 |
+------+-------+------+
4 rows in set

 B表

所用查询语句为：

select z_code, A.mgr mgr, sum(pigs) pigs from A, B where A.mgr = B.mgr group by A.mgr order by pigs desc;

下面是建表和插入语句的SQL：

create database pig_store;
use pig_store;

create table A(
    z_code varchar(8),
    city varchar(4),
    mgr varchar(16)
);
create table B(
    part varchar(8),
    mgr varchar(16),
    pigs int(5)
);

insert into A values ( '010', 'BJ', 'wang'), ( '021', 'HB', 'zhang' );
insert into B values ( '001', 'wang', 20 ), ( '002', 'wang', 50 ), ( '011', 'zhang', 49 ), ( '012', 'zhang', 36 );