sql - 计算单个数据组

Question

对于给定的表

1st column=producer
2nd column=type

A a
A a
A a
A b

B c
B c
B c

我想计算非重复组的数量。输出应该等于A=2 B=1。

我不知道如何做到这一点:(

Answer 1

只需使用count()：

select producer, count(distinct type)
from yourtable
group by producer

Answer 2

尝试这个：

 select producer, count(distinct type) from table group by  producer

Answer 3

这样的事情应该可以解决问题：

SELECT producer, COUNT(DISTINCT type)
FROM YOUR_TABLE
GROUP BY producer

这应该会给你类似的结果：

producer  COUNT(DISTINCT type)
--------  --------------------
A         2
B         1

Answer 4

SELECT producer, COUNT(producer)
FROM table
GROUP BY producer, type