如果沒有資質匹配,如何顯示0?如何在計數中顯示0?
我當前的查詢是:
select s.sname, count(*) as number
from sailor s, boat b
where s.rating >= b.rating
group by s.sname
order by number desc;
而且我得到的結果是:
a 3
b 3
c 2
然而,這是不是真的就是我想要的目的。我想顯示的結果是這樣的:
a 3
b 3
c 2
d 0
e 0
我試圖改變計數()到ISNULL(計數(),0)或合併(COUNT(*),0),但它不糾正這個案例。
CREATE TABLE sailor (
sname character varying primary key,
rating integer
);
create table boat (
bname character varying primary key,
color character varying,
rating integer
);
您可以發佈水手和船的結構? – 2014-11-02 03:42:35