SQL查詢來一天，但與其他條件

Question

我有數據是這樣的：

| visitor_id | time  | my_flag | 
| 1   | 01-01-2017 | 1  | 
| 2   | 01-01-2017 | 1  | 
| 1   | 01-02-2017 | 2  | 
| 3   | 01-02-2017 | 2  | 

等等

我希望將所有遊客在一天內，但基於一個標誌。該標誌可以有兩個值，1或2。所以，我需要這樣的東西

| 12 | 01-01-2017 | 1 | 
| 10 | 01-01-2017 | 2 | 
| 34 | 01-02-2017 | 1 | 

我

select v.visitor_id v.time, v.flag 
from my_table as v 
group by DAY(v.time) having flag=1; 

但我無法弄清楚如何添加多個條件（標誌= 1標誌= 2）？任何指針？

Answer 1

嘗試這樣的事情

select v.visitor_id v.time, v.flag 
from my_table as v 
where v.flag in (1,2) 
group by DAY(v.time), v.flag 

Answer 2

SELECT v.time, 
     v.flag, 
     COUNT(v.visitor_id) 
FROM my_table as v 
GROUP BY v.time, 
     v.flag;`