我有4张tablepc、笔记本、智能手机和产品:
select * from Notebook;
+------------+----------+-----------+----------+-------------+----------+-------+
| model_name | cpu_core | cpu_speed | hdd_type | screen_size | hdd_size | price |
+------------+----------+-----------+----------+-------------+----------+-------+
| GP62M | 6 | 3500 | SSD | 17 | 256 | 2300 |
| GE62 | 4 | 3300 | SSD | 15 | 128 | 2100 |
| GL62 | 4 | 3000 | SSD | 15 | 128 | 1900 |
| Vostro | 4 | 2200 | HDD | 17 | 500 | 1800 |
| Inspiron | 4 | 1600 | HDD | 15 | 500 | 1600 |
| Air | 4 | 1800 | SSD | 13 | 512 | 3000 |
| Swift 5 | 4 | 4000 | SSD | 14 | 512 | 2750 |
| Swift 6 | 6 | 4000 | SSD | 17 | 512 | 2950 |
+------------+----------+-----------+----------+-------------+----------+-------+
select * from PC;
+------------+----------+-----------+------+----------+-------+
| model_name | cpu_core | cpu_speed | ram | hdd_size | price |
+------------+----------+-----------+------+----------+-------+
| XPS | 6 | 2200 | 16 | 1000 | 2100 |
| Surface | 4 | 2000 | 32 | 2000 | 2400 |
| Magnus | 4 | 2000 | 6 | 2000 | 1800 |
| Aurora A6 | 4 | 2200 | 32 | 2200 | 2300 |
| Trudent 3 | 4 | 2400 | 16 | 2400 | 2000 |
+------------+----------+-----------+------+----------+-------+
select * from Product;
+-----------+---------------+------------+
| vendor | model_name | type |
+-----------+---------------+------------+
| DELL | XPS | PC |
| DELL | Trudent 3 | PC |
| DELL | Aurora A6 | PC |
| NoteShop | Surface | PC |
| NoteShop | Magnus | PC |
| LapShop | GP62M | Notebook |
| LapShop | GE62 | Notebook |
| LapShop | GL62 | Notebook |
| LapShop | Vostro | Notebook |
| LapShop | Inspiron | Notebook |
| AppleShop | Air | Notebook |
| AppleShop | 3G | Smartphone |
| AppleShop | 4G | Smartphone |
| AppleShop | 5 | Smartphone |
| AppleShop | 5G | Smartphone |
| Xiaomi | Redmi note 3 | Smartphone |
| Xiaomi | Redmi note 4 | Smartphone |
| Xiaomi | Redmi note 5 | Smartphone |
| Samsung | Galaxy note 5 | Smartphone |
| Samsung | Galaxy note 8 | Smartphone |
| NoteShop | Swift 5 | Notebook |
| NoteShop | Swift 6 | Notebook |
+-----------+---------------+------------+
select * from Smartphone;
+---------------+----------+-----------+------------+---------+------+-------+
| model_name | cpu_core | cpu_speed | flash_size | OS | lte | price |
+---------------+----------+-----------+------------+---------+------+-------+
| 3G | 2 | 1200 | 8 | Ios | - | 450 |
| 4G | 3 | 1600 | 8 | Ios | + | 850 |
| 5 | 3 | 1800 | 16 | Ios | + | 1250 |
| 5G | 4 | 2000 | 8 | Ios | + | 1350 |
| Redmi note 3 | 3 | 2000 | 8 | Android | + | 800 |
| Redmi note 4 | both 4 | 2200 | 16 | Android | + | 1200 |
| Redmi note 5 | 6 | 2400 | 16 | Android | + | 1300 |
| Galaxy note 5 | 6 | 2200 | 8 | Android | + | 1100 |
| Galaxy note 8 | 8 | 2400 | 8 | Android | + | 1400 |
+---------------+----------+-----------+------------+---------+------+-------+
我只需要从3个表中选择一个最大价格-个人电脑,智能手机和笔记本电脑,这不是关于创建另一个表的最大值,其主要思想是显示使用命令只。我试图使用子查询,但似乎我有两只左手。
1条答案
按热度按时间tyg4sfes1#
使用
UNION
在子查询中。