Question

proc SQL;


CREATE TABLE DATA.DUMMY AS
SELECT *,  
  CASE 
  WHEN (Discount IS NOT NULL) 
    THEN (Total_Retail_Price - (Total_Retail_Price * Discount)) * Quantity AS Rev
  ELSE (Total_Retail_Price * Quantity) AS Rev
  END

FROM DATA.Cumulative_Profit_2013 AS P

;

我试图将潜在的NULL列作为Revenue表达式的一部分。但我的案例陈述引发了一些问题。我已经检查了其他例子，但我看不出为什么会有所帮助

Answer 1

看起来您可以使用COALESCE来实现您的目标，而无需明确的条件：

SELECT *,  
  (Total_Retail_Price - (Total_Retail_Price * COALESCE(Discount, 0))) * Quantity AS Rev
FROM DATA.Cumulative_Profit_2013 AS P

Answer 2

不知道SAS，正常的SQL语法是：

SELECT *,  
  CASE 
   WHEN (Discount IS NOT NULL) 
    THEN (Total_Retail_Price - (Total_Retail_Price * Discount)) * Quantity 
   ELSE (Total_Retail_Price * Quantity)
  END AS Rev

即，在case表达式结束后使用列别名。

Answer 3

作为一个说明，我会把它写成：

SELECT p.*,  
       (Total_Retail_Price * (1 - COALESCE(Discount, 0)) * Quantity) AS Rev 
FROM DATA.Cumulative_Profit_2013 AP

我发现原始表达式中Total_Retail_Price的重复更难以遵循。

注意：所有答案都适用于SAS。

SQL Case语句NULL列

3 个答案: