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

A little improvement to the selected answer would be not to have to define those variables. So this query can be solved in just a single statement:

SELECT COUNT(*) cnt, user
FROM (
    SELECT @num := @num + (@name != user) as number,
           @name := user as user
    FROM t, (select @num := 0, @name := '') as s
    ORDER BY id
) x
GROUP BY number

Output:

| CNT |     USER |
|-----|----------|
|   3 | zhangsan |
|   3 |     lisi |
|   2 | zhangsan |

Fiddle here