Question

我正在编写一个在insert语句中有多个select语句的查询

    INSERT INTO dbo.Products 
    (ProductName, 
     SupplierID, 
     CategoryID, 
     UnitsInStock, 
     UnitsOnOrder, 
     ReorderLevel, 
     Discontinued)
VALUES  
    ('Twinkies' , 
     (SELECT SupplierID FROM dbo.Suppliers WHERE CompanyName = 'Lyngbysild'),
     (SELECT CategoryID FROM dbo.Categories WHERE CategoryName = 'Confections'), 
     0, 
     0, 
     10, 
     0)

实际上它给出了错误

Msg 1046, Level 15, State 1, Line 4
Subqueries are not allowed in this context. Only scalar expressions are allowed.
Msg 102, Level 15, State 1, Line 4
Incorrect syntax near ','.

这两个select语句只返回一个值。

Answer 1

只需将VALUES更改为SELECT并删除外括号。

INSERT INTO dbo.Products 
(ProductName, 
 SupplierID, 
 CategoryID, 
 UnitsInStock, 
 UnitsOnOrder, 
 ReorderLevel, 
 Discontinued)
SELECT  
'Twinkies' , 
 (SELECT SupplierID FROM dbo.Suppliers WHERE CompanyName = 'Lyngbysild'),
 (SELECT CategoryID FROM dbo.Categories WHERE CategoryName = 'Confections'), 
 0, 
 0, 
 10, 
 0

您可能还需要在子表达式上使用TOP 1，但这会产生不同的错误消息：子查询返回了多个值。

Answer 2

错误信息正确，因为

SELECT SupplierID FROM dbo.Suppliers WHERE CompanyName = 'Lyngbysild'

可以（技术上）返回多行，它应该在列中显示哪一行？

如果您知道此子查询只返回一行，那么告诉数据库采取第一行。

SELECT TOP 1 SupplierID FROM dbo.Suppliers WHERE CompanyName = 'Lyngbysild'

Insert语句中的Multiple Select语句中的错误

2 个答案: