SQL Server 中是否有一个 Max 函数，它接受两个值，例如 .NET 中的 Math.Max?

2022-01-31 00:00:00 max sql sql-server

我想写一个这样的查询:

I want to write a query like this:

SELECT o.OrderId, MAX(o.NegotiatedPrice, o.SuggestedPrice)
FROM Order o

但这不是 MAX 函数的工作原理，对吧?它是一个聚合函数，因此它需要一个参数，然后返回所有行的 MAX.

But this isn't how the MAX function works, right? It is an aggregate function so it expects a single parameter and then returns the MAX of all rows.

有人知道我的方法吗?

推荐答案

如果你想拥有与你的示例类似的语法，你需要创建一个 User-Defined Function，但你能做到吗正如其他人所说的那样，您想用 CASE 语句相当容易地内联.

You'd need to make a User-Defined Function if you wanted to have syntax similar to your example, but could you do what you want to do, inline, fairly easily with a CASE statement, as the others have said.

UDF 可能是这样的:

create function dbo.InlineMax(@val1 int, @val2 int)
returns int
as
begin
  if @val1 > @val2
    return @val1
  return isnull(@val2,@val1)
end

...你会这样称呼它...

... and you would call it like so ...

SELECT o.OrderId, dbo.InlineMax(o.NegotiatedPrice, o.SuggestedPrice) 
FROM Order o

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