mysql groupy by group by multiple fields

member employee table 
----------------------- 
company | group | name 
----------------- -------- 
 Company 1 | A Team | Zhang San 
 Company 1 | A Team | Li Si 
 Company 1 | A Team | Wang Wu 
 Company 1 | 
 B 
 Team | | Team A | Xiao Ming

1. Count how many employees are there in each company?

SELECT `company`, Count(*) FROM `member` GROUP BY `company` ;

The following results are obtained: 

company | Count 

------------------------------ 
 Company 1 | 4 
--------- --------------------- 
 Company 2 | 2

2. Count how many employees are in each team under each company?

SELECT `company`, Count(*) FROM `member` GROUP BY `company` , `group` ;

The following results are obtained: 

company | group | Count 

------------------------------ 
 company 1 | A team | 3 
---- -------------------------- 
 Company 1 | Team B | 1 
----------------- ------------- 
 Company 2 | Team A | 2

GROUP BY X : Put all records with the same value of the X field into one group.

GROUP BY X, Y : Put all records with the same X field value and Y field value into one group.