如何在SQL中有效地计算列值的出现而不重复？

Question

在找到计数时，我算作：

Serial No  |   Countt
------------------------
10467      |     1
10468      |     1
10468      |     2
10469      |     1

我想查询查找计数如下：

Serial No  |  Countt
----------------------
10467      |     1
10468      |     2
10469      |     1

我用下面的查询：

(SELECT Distinct Tax_Percentage, Serial_No, 
COUNT(*) OVER (PARTITION BY Tax_Percentage,Serial_No ) AS Countt
FROM sales_detail Where Serial_No>=10467)
Order By  Serial_No

Answer 1

SELECT id，attribute，COUNT（attribute）FROM mytable GROUP BY属性

This can help you

Answer 2

试试这个：因为Taxpercent，你知道我们无法获得独一无二的，如果你跳过那一栏就可以轻松获得：

SELECT distinct TaxPrcnt,SrNo,count(CAST(ISNULL(SrNo,0) as int)) OVER(PARTITION BY SrNo 
ORDER BY SrNo) AS Countt
FROM #temp

Answer 3

按两列分组

SELECT Tax_Percentage, Serial_No, COUNT(*) Countt 
FROM sales_detail 
Where Serial_No>=10467) 
Group by Tax_Percentage, Serial_No
Order By Serial_No

我不确定你要实现什么，但如果你想找到serial_no的出现，你需要按此列对计数进行分区。

SELECT Tax_Percentage, Serial_No, 
        COUNT(*) over(partition by Serial_No) Countt 
FROM sales_detail 
Where Serial_No>=10467) 
Order By Serial_No