查找分配給另一個字段值的計數

Question

Create table t1 (col1 (number), col2 (number), col3 (number); 

Insert into t1 values (1,1,1); 
Insert into t1 values (1,2,5); 
Insert into t1 values (1,3,1); 
Insert into t1 values (2,1,1); 
Insert into t1 values (2,1,1); 

Desired result 
col1 col2 
    1  3 
    2  2 

我需要返回col1中的值和col 2中找到的每個不同col1值的計數值。不需要col3

Answer 1

select col1, count(col1) from t1 
group by col1