如果SQL中没有记录匹配，如何返回零 [英] How can I return zero if no record is match in SQL

问题描述

嗨!!!!!

i尝试获取产品名称为笔记本电脑的最大ID

如果根据产品名称找到ID，则返回ID

但我想如果根据产品名称找不到ID那么sql返回零

请任何人告诉我该怎么做。

我正在使用代码，但可能不是很好



我尝试了什么：

hi!!!!!
i try to get maximum ID where product name is 'Laptop'
if it find ID according to product name then it will return ID
but i want if no ID is find according to product name then sql return zero
please any one tell me how can i do this.
I'm using a code but may be it is not fine

What I have tried:

ALTER PROCEDURE [dbo].[USP_Select_Current_PurchaseItem_QtyPurRate_BAseOnItemName]
(
@ItemName		nvarchar(50)
)
AS
BEGIN
	SELECT      
     max(isnull,([Id]),0) as 'CurrentlyaddeItemId'
   
  FROM [dbo].[Purchasing_Items_Hist]
  where Itemtype=@ItemName
END

推荐答案

你有正确的想法，只是错误的语法。而不是IsNull我相信你应该使用COALESCE。



你想知道MAX（id）何时为空。这样做：

You have the right idea, just the wrong syntax. And instead of IsNull I believe you should be using COALESCE.

You want to know when MAX(id) is null. Do this:

SELECT      
     COALESCE(max([Id]), 0) as 'CurrentlyaddeItemId'
   
  FROM [dbo].[Purchasing_Items_Hist]
  where Itemtype=@ItemName

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