如何在T-SQL中分配多個內聯變量？

Question

我想從子查詢中選擇多個變量以便稍後使用。這裏是我的代碼：

DECLARE @MarketplaceName VARCHAR(50), 
    @ProductFieldID INT, 
    @FromValue VARCHAR(255) = (
     SELECT mcvm.MarketplaceName, 
      mcvm.ProductFieldID, 
      mcvm.FromValue 
     FROM [Meta].[MarketplaceCategoryValueMapping] AS mcvm 
     WHERE mcvm.MarketplaceCategoryValueMappingID = @MapID 
     ) 

我收到以下錯誤信息：

只有一個表達式可以在選擇列表時，子查詢不與EXISTS引入的指定。

我試圖映射@MarketplaceName從mcvm.MarketplaceName等

我想是沒有寫每個變量的多個SELECT語句。

Answer 1

你想要做到這一點嗎？

DECLARE @MarketplaceName VARCHAR(50), 
     @ProductFieldID INT, 
     @FromValue VARCHAR(255) 
SELECT @MarketplaceName = mcvm.MarketplaceName, 
     @ProductFieldID  = mcvm.ProductFieldID, 
     @FromValue   = mcvm.FromValue 
FROM [Meta].[MarketplaceCategoryValueMapping] AS mcvm 
WHERE mcvm.MarketplaceCategoryValueMappingID = @MapID 

Answer 2

這就是你如何做到的。此外，這不是一個子查詢，它只是一個查詢。

DECLARE @MarketplaceName VARCHAR(50), 
     @ProductFieldID INT, 
     @FromValue VARCHAR(255) 


SELECT @MarketplaceName = mcvm.MarketplaceName, 
     @ProductFieldID = mcvm.ProductFieldID, 
     @FromValue = mcvm.FromValue 
FROM [Meta].[MarketplaceCategoryValueMapping] AS mcvm 
WHERE mcvm.MarketplaceCategoryValueMappingID = @MapID