幫助中寫一個SQL查詢

Question

我想編寫一個查詢，將在表中獲取玩家的數量在一個運動隊對每一個國家：

我有一個表具有以下字段

country | sports_team | player_name 

我要顯示與此類似

country | sports_team | number_of_players 

即reulst我想遍歷所有國家，以及在SPORTS_TEAM每一個變化，我想記錄numm隊中的球員。

樣品表：

country | sports_team | player_name 
c1  | teamA  | name1 
c1  | teamA  | name2 
c1  | teamB  | name3 
c2  | teamC  | name4 
c2  | teamC  | name5 

樣品結果

country | sports_team | number_of_players 
c1  | teamA  | 2 
c1  | teamB  | 1 
c2  | teamC  | 2 

我是新來編寫SQL查詢，我不知道如何PROCEDE，任何幫助將不勝感激！

Answer 1

試試這個：

SELECT country, sports_team, COUNT(*) AS number_of_players 
FROM yourtable 
GROUP BY country, sports_team 
ORDER BY country, sports_team; 

Aggregate查詢，如COUNT對於這種數據處理的關鍵。

Answer 2

使用GROUP BY：

SELECT country, sports_team, COUNT(*) 
FROM whatever_your_table_is  
GROUP BY country, sports_team 

Answer 3

試試這個：

SELECT 
    Country, Sports_Team, COUNT(player_name) AS number_of_players 
FROM 
    YourTable 
GROUP BY 
    Country, Sports_Team 

Answer 4

select country, sports_team, count(*) from <your table> group by country, sports_team 

Answer 5

select 
    country, 
    sports_team, 
    count(*) number_of_players 
from table 
group by country, sports_team 

Answer 6

無需環路，只是彙總。

SELECT country, sports_team, COUNT(*) 
FROM myTable 
GROUP BY country, sports_team 

神奇的是在COUNT(*)和GROUP BY條款