Question

在Proc sql中使用嵌套大小写，我需要根据指定的年份和月份获取列的值。例如 - 如果年份是2018年，月份是12月那么它应该返回列x201811的值，如果它是null，它应该返回零。我在下面写的代码给出了语法错误。请提出解决方案。

CASE  WHEN (( Year(date) = 2018 ) AND ( Month(date) = 12 )) THEN x201811 
     WHEN x201811 IS NULL THEN 0
   ELSE x201811
   WHEN ((Year(date)=2018) AND (Month(Date)=11)) THEN x201810
    WHEN x201810 IS NULL THEN 0
   ELSE x201810

Answer 1

您可以使用COALESCE函数使第一个非空值成为指定值。

CASE
  WHEN (( Year(date) = 2018 ) AND ( Month(date) = 12 )) 
  THEN coalesce (x201811, 0)

  WHEN ((Year(date)=2018) AND (Month(Date)=11)) 
  THEN coalesce (x201810, 0)

  ELSE coalesce (x201810, 0)
END as got_a_value

替代方法是嵌套CASE语句

CASE
  WHEN (( Year(date) = 2018 ) AND ( Month(date) = 12 )) 
  THEN CASE WHEN x201811 is null then 0 else x201811 end

  WHEN ((Year(date)=2018) AND (Month(Date)=11))
  THEN CASE WHEN x201810 is null then 0 else x201810 end

  ELSE ...
END as got_a_value

Proc SQL：CASE WHEN嵌套

1 个答案: