如何在SQL中使用Subinct with Order by SubString？

Question

如何在SQL中使用Distinct with SubString？

我的查询是

  SELECT 
 Distinct [Units Period]   
 FROM Table_Name
ORDER BY RIGHT([Units Period], 4) DESC , SUBSTRING([Units Period], 5, 2) DESC

但它没有用。

Answer 1

错误是：ORDER BY items must appear in the select list if SELECT DISTINCT is specified.

使用GROUP BY

重写查询

SELECT 
  [Units Period]   
FROM 
  Table_Name
GROUP BY
  [Units Period]   
ORDER BY 
  RIGHT([Units Period], 4) DESC , 
  SUBSTRING([Units Period], 5, 2) DESC

或在distinct之后添加所有列：

SELECT 
  distinct
  [Units Period],
  RIGHT([Units Period], 4), 
  SUBSTRING([Units Period], 5, 2)
FROM 
  Table_Name
ORDER BY 
  RIGHT([Units Period], 4) DESC , 
  SUBSTRING([Units Period], 5, 2) DESC

Answer 2

您可以将查询重写为：

 Select [Units Period] 
 From (
       SELECT 
       Distinct [Units Period]   
       FROM Table_Name) T
ORDER BY RIGHT([Units Period], 4) DESC , SUBSTRING([Units Period], 5, 2) DESC