错误：在此上下文中不允许子查询。只允许标量表达式

Question

我一直收到这个错误：

  

在此上下文中不允许使用子查询。只有标量表达式   允许

代码：

Create table SaleFact
(
CustomerKey int not null,
EmployeeKey int not null,
ProductKey int not null,
ShipperKey int not null,
TimeKey int not null,
LineItemQuantity int null constraint "DF_SaleFact_LineItemQuantity" Default(1),
LineItemDiscount money null constraint "DF_SaleFact_LineItemDiscount" Default(0),
LineItemFreight money null,
LineItemTotal money null,
Constraint "PK_SaleFact" Primary key Clustered
(CustomerKey,EmployeeKey,ProductKey,TimeKey),
Constraint "Fk_CustomerKey" Foreign Key
(
    "CustomerKey"
    )
    References "dbo"."CustomerDimension"(
    "CustomerKey"),
Constraint "Fk_EmployeeKey" Foreign key
(

    "EmployeeKey")
    References "dbo"."EmployeeDimension"(
    "EmployeeKey"),
Constraint "Fk_ProductKey" Foreign key
(
    "ProductKey")
    References "dbo"."ProductKey"(
    "ProductKey"),
Constraint "Fk_ShipperKey" Foreign key
(
    "ShipperKey")References"dbo"."ShipperKey"(
    "ShipperKey"),
Constraint "Fk_TimeKey" Foreign key
(
    "TimeKey")References "dbo"."TimeKey"(
    "TimeKey"),

Constraint "ck_LineItemQuantity" check(LineItemQuantity>=0),
Constraint "ck_LineItemDiscount" check(LineItemDiscount>=0 and LineItemDiscount<=1),
Constraint "ck_LineItemFreight" check(LineItemFreight>=0),
Constraint "ck_LineItemTotal" check(LineItemTotal =LineItemQuantity* (select ListUnitPrice from ProductDimension ))  //this lineitemtotal is the one where I kept getting an error saying that subqueries are not allowed in this context. Because I'm trying to that listunitprice from the table  name ProductDimension

）