c# - 命名空间中不存在类型或命名空间名称

Question

我在 .cs 文件中有以下代码，但遇到以下错误，我们将不胜感激。

using System.Data.Entity;

namespace Assignment2.Models
{
    public class TicketBookingEntities : DbContext
    {
        public DbSet<Performance> Performances { get; set; }
        public DbSet<Production> Productions { get; set; }
    }
}

错误:

Error   1   The type or namespace name 'Entity' does not exist in the namespace 'System.Data' (are you missing an assembly reference?)
Error   2   The type or namespace name 'DbContext' could not be found (are you missing a using directive or an assembly reference?)
Error   3   The type or namespace name 'DbSet' could not be found (are you missing a using directive or an assembly reference?)
Error   4   The type or namespace name 'DbSet' could not be found (are you missing a using directive or an assembly reference?)

Answer 1

确保您的项目包含对 EntityFramework.dll 的引用。
请参阅主题在 Visual C# 中添加引用 this link如果您不知道如何添加引用。