MYSQL - 按分组计算

Question

假设这样的表

domain       | city      | number
-------------|-----------|-------
example.com  | rome      | 11111 <--,
example1.com | rome      | 11111    |_ this two should be counted as 1
example2.com | rome      | 11111    |
example.com  | rome      | 11111 <--'
example.com  | amsterdam | 11111
example2.com | rome      | 22222
example.com  | uk        | 22222
example.com  | amsterdam | 22222 <--._ this two should be counted as 1
example.com  | amsterdam | 22222 <--'

我想输出类似以下结果11111, total = 4和22222, total = 3

到目前为止，我有这个查询，但当然不能正常工作！ :(

SELECT number, COUNT(number) as total FROM table GROUP BY city, domain

Answer 1

您可以在预处理表表达式上使用COUNT()来消除重复项，如下所示：

select number, count(*)
from (
  select distinct domain, city, number from my_table
) x
group by number

Answer 2

你可以group by number：

select number, count(distinct concat(domain, '-', city)) total
from tablename
group by number

结果：

number  total
11111   4
22222   3