Count + Distinct SQL Query

Question

我有一張研究表

researcher    award

 person1      award1
 person1      award2
 person2      award3

我想得到的是根據研究人員計算獎項，但研究人員不應該重復。 所以在這個例子中。 結果應該是

 2

Coz award1和award2是同一個人+ award3，是另一個人。

我已經試過了

SELECT count(award) from research where researcher=(select distinct(researcher) from researcher)

但它說

ERROR:  more than one row returned by a subquery used as an expression

那么任何替代解決方案或變化？

Answer 1

這將給你研究員和計數

select researcher, count(*) as c
from table
group by researcher

也許你只想要獲獎？

select researcher, count(*) as c
from table
where award is not null
group by researcher

Answer 2

你可以做一個小組並計算不同的獎項。

SELECT count(distinct award) from research group by researcher

Answer 3

您只需要使用GROUP BY ：

SELECT    COUNT( DISTINCT Award ) AS awardCount 

FROM      Research 

GROUP BY  Researcher

Answer 4

select count(*) from (select researcher, count(*) 
from MyTable
group by researcher) as tempTable;