帮助中写一个SQL查询

Question

我想编写一个查询，将在表中获取玩家的数量在一个运动队对每一个国家：

我有一个表具有以下字段

country | sports_team | player_name 

我要显示与此类似

country | sports_team | number_of_players 

即reulst我想遍历所有国家，以及在SPORTS_TEAM每一个变化，我想记录numm队中的球员。

样品表：

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

样品结果

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

我是新来编写SQL查询，我不知道如何PROCEDE，任何帮助将不胜感激！

Answer 1

试试这个：

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

Aggregate查询，如COUNT对于这种数据处理的关键。

Answer 2

使用GROUP BY：

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

Answer 3

试试这个：

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

无需环路，只是汇总。

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

神奇的是在COUNT(*)和GROUP BY条款