How to combine near same item by SQL?

Question

I have some data in database:

id user 
1 zhangsan 
2 zhangsan 
3 zhangsan 
4 lisi 
5 lisi 
6 lisi 
7 zhangsan 
8 zhangsan 

I want keep order, a

Answer 1

I think what you are looking for is to COUNT(ID):

SELECT COUNT(ID) FROM table GROUP BY user