导入
用数据进行数学运算
使用聚合函数来汇总数据。
表格
| ID | 姓名 | 年龄 | 城市 |
|---|---|---|---|
| 1 | Aisha | 30 | 卡拉奇 |
| 2 | Dan | 24 | 纽约 |
| 3 | Fatima | 27 | 拉合尔 |
| 4 | Lee | 22 | 首尔 |
1SELECT COUNT(*) FROM people;
1SELECT SUM(age), AVG(age) FROM people;
1SELECT MIN(age), MAX(age) FROM people;
1SELECT AVG(age) AS average_age FROM people;