Question

假设我有以下问题：

SELECT DISTINCT(Value1,value2,value3) From table1

并获得类似

的内容

        #   value1  value2  value3
--------------------------------------
        1.  result1 result1 result2
        2.  result1 result2 result2
        3.  result5 result6 result7

如何添加一个额外的列，告诉我出现这些唯一值组合的次数，例如（最后一列是它出现的次数）：

 #    value1  value2  value3      #occurred
--------------------------------------
 1.  result1 result1 result2      15
 2.  result1 result2 result2      25
 3.  result5 result6 result7      35

Answer 1

SELECT    Value1,value2,value3,count(*)
From      table1
group by  Value1,value2,value3

Answer 2

使用group by代替distinct。然后，您可以使用count。

select value1, value2, value3, count(*) as occurred
from table1
group by value1, value2, value3;

SQLite中的演示。

sqlite> select * from table1 order by value1, value2, value3;
value1      value2      value3    
----------  ----------  ----------
1           1           2         
1           1           2         
1           2           2         
1           2           2         
1           2           2         
5           6           7         

sqlite> select value1, value2, value3, count(*) as '#occurred' from table1 group by value1, value2, value3;
value1      value2      value3      #occurred 
----------  ----------  ----------  ----------
1           1           2           2         
1           2           2           3         
5           6           7           1

计算SQL中不同列的数量

2 个答案: