聚集了兩條表

Question

我有兩個表

nameTB包含：

id | name | gender | nationalityid 

nationalityTB包含：

nationalityid | nationalityname

我想創建SQL查詢返回的結果：

nationalityname   female    male  total 
UK       10     5   15 
USA      11     7   18 

Answer 1

您應該能夠通過連接表，使用該聚合函數條件邏輯（如CASE表達式）輕鬆獲得的結果：

select nt.nationalityname, 
    sum(case when nm.gender = 'Female' then 1 else 0 end) Female, 
    sum(case when nm.gender = 'Male' then 1 else 0 end) Male, 
    count(*) Total 
from nationalityTB nt 
left join nameTB nm 
    on nt.nationalityid = nm.nationalityid 
group by nt.nationalityname; 

見SQL Fiddle with Demo您正在使用什麼數據庫平臺