错误 40 edmx 文件 MVC:类型 decimal(18，0) 未使用命名空间或别名限定

我对MVC概念很陌生。我正在使用Microsoft Visual Studio Express 2013 for Web和SQL Server LocalDb v11。到目前为止，我没有遇到任何问题。但后来我将数据库中的价格字段从实数更改为十进制（18，0）。我收到有关 edmx 文件的错误：

Error 40: The Type decimal(18,0) is not qualified with a namespace or alias. Only primitive types can be used without qualification.

我已经尝试在我的 edmx 文件中使用类型"十进制"和 int（只是为了看看它是否有效），但仍然出现相同的错误。

我很欣赏每一个答案。

数据库部分：

CREATE TABLE [dbo].[Item] (
    [Id]        INT            NOT NULL,
    [DepartmentId] INT            NOT NULL,
    [Name]       NVARCHAR (50)  NOT NULL,
    [Description]      NVARCHAR (MAX) NOT NULL,
    [Price]      DECIMAL           NOT NULL,
    [Quantity]  INT            NOT NULL,
    [AuthorId]   INT            NULL,
    PRIMARY KEY CLUSTERED ([Id] ASC),
    CONSTRAINT [FK_Item_ToDepartment] FOREIGN KEY ([DepartmentId]) REFERENCES [dbo].[Department] ([Id]),
    CONSTRAINT [FK_Item_ToAuthor] FOREIGN KEY ([AuthorId]) REFERENCES [dbo].[Author] ([Id])
);

型号类别：

       namespace WebStore.Models
{
    using System;
    using System.Collections.Generic;
    public partial class Item
    {
        public Item()
        {
            this.Cart = new HashSet<Cart>();
        }
        public int Id { get; set; }
        public int DepartmentId { get; set; }
        public string Name { get; set; }
        public string Description { get; set; }
        public decimal Price { get; set; }
        public int Quantity { get; set; }
        public Nullable<int> AuthorId { get; set; }
        public virtual Author Author { get; set; }
        public virtual Department Department { get; set; }
        public virtual ICollection<Cart> Cart { get; set; }
    }
}    

以及 edmx 文件中我收到错误 40 的部分：

<EntityType Name="Item">
      <Key>
        <PropertyRef Name="Id" />
      </Key>
      <Property Name="Id" Type="Int32" Nullable="false" />
      <Property Name="DepartmentId" Type="Int32" Nullable="false" />
      <Property Name="Name" Type="String" MaxLength="50" FixedLength="false" Unicode="true" Nullable="false" />
      <Property Name="Description" Type="String" MaxLength="Max" FixedLength="false" Unicode="true" Nullable="false" />
      <Property Name="Price" Type="decimal(18,0)" Nullable="false" />
      <Property Name="Quantity" Type="Int32" Nullable="false" />
      <Property Name="AuthorId" Type="Int32" />
      <NavigationProperty Name="Author" Relationship="Self.FK_Item_ToAuthor" FromRole="Izdelek" ToRole="Author" />
      <NavigationProperty Name="Department" Relationship="Self.FK_Item_ToDepartment" FromRole="Izdelek" ToRole="Departmetn" />
      <NavigationProperty Name="Cart" Relationship="Self.FK_Cart_ToItem" FromRole="Izdelek" ToRole="Cart" />
    </EntityType>