Question

我在MY SQL服务器中创建了一个视图，我需要使用CASE条件才能满足要求。

select 
  cast([SIR Per Occ] as float) * 1000000 as [SIR Per Occ],
  cast([SIR Agg] as float) * 1000000 as [SIR Agg],
  cast([Per Occ Limit Between] as float) * 1000000 as [Per Occ Limit Between],
  cast((cast([SIR Per Occ] as float)) + (cast([Per Occ Limit Between] as float)) as float) * 1000000 as [Policy Occ Attachment],
  cast((cast([SIR Agg] as float)) + (cast([Per Occ Limit Between] as float)) as float) * 1000000 as [Policy Agg Attachment]
from IT.dbo.Policy_find

但是在我的任务中，如果[Per Occ Limit Between]是NULL值，那么我需要假设它为零，上面的代码应该按照以下逻辑运行：

Policy Occ Attachment = [SIR Per Occ]
Policy Agg Attachment = [SIR Agg]

如何在不使用where条件的情况下在select子句中实现此类场景？

Answer 1

只需将CASE与列定义一起使用，而不是列名称（CASE MSDN here）。

EDIT（对于SQL Server）：如果要删除NULL值，可以使用ISNULL(YOUR_EXPRESSION, '')

Answer 2

我无法确定它是我的“SQL服务器”还是“我的SQL”服务器。

但实际上，对于这个特定的查询并不重要。

使用COALESCE

select 
  cast([SIR Per Occ] as float) * 1000000 as [SIR Per Occ],
  cast([SIR Agg] as float) * 1000000 as [SIR Agg],
  cast([Per Occ Limit Between] as float) * 1000000 as [Per Occ Limit Between],
  cast((cast([SIR Per Occ] as float)) + (cast(COALESCE([Per Occ Limit Between],0) as float)) as float) * 1000000 as [Policy Occ Attachment],
  cast((cast([SIR Agg] as float)) + (cast([Per Occ Limit Between] as float)) as float) * 1000000 as [Policy Agg Attachment]
from IT.dbo.Policy_find

如何在SQL视图中创建新列时使用条件

2 个答案: