sql - SQL Plus "case" 关键字

Question

任何人都可以帮助我使用 SQL Plus 的“case”语句的正确语法吗？

Select 
sum(case "REQUEST AGE" when >= 60 then 1 else 0) as "60+ Days",
sum(case "REQUEST AGE"  when >= 30 and case when "REQUEST AGE" < 60 then 1 else 0) as "30-    60 Days",
sum (case "REQUEST AGE" when < 30 then 1 else 0) as "Less Than 30 Days",
"SECTOR"
FROM Schema.APPDATA
Where Schema.APPDATA."SECTOR" like '%X%'

我对 SQL 比较陌生，而且我从来没有写过这样的查询。我想要列请求年龄大于 60、介于 30 和 60 之间且小于 30 的情况的总和，因为 3 列按列扇区分组

Answer 1

每个CASE语句都必须END在(). 您可以在CASE WHEN <condition> THEN此处使用语法：

Select 
  sum(case when "REQUEST AGE" >= 60 then 1 else 0 END) as "60+ Days",
  /* And in here, don't repeat the CASE keyword. Both parts of the expression are connected by AND */
  sum(case when "REQUEST AGE" >= 30 and "REQUEST AGE" < 60 then 1 else 0 END) as "30-    60 Days",
  sum (case when "REQUEST AGE" < 30 then 1 else 0 END) as "Less Than 30 Days",
  "SECTOR"
FROM Schema.APPDATA
Where Schema.APPDATA."SECTOR" like '%X%'

Answer 2

您需要使用CASE WHEN [expression]... THEN而不是CASE [variable] WHEN [value] THEN ...：

Select 
sum(case WHEN "REQUEST AGE" >= 60 then 1 else 0 end) as "60+ Days",
....

此外，在您的情况下，这似乎count比sum您根本不需要更合适else。