您没有从DbContext继承。

 public class OrderDetailsContext : DbContext
    {
        public OrderDetailsContext(DbContextOptions<OrderDetailsContext> options) : base(options)
        { }

        //defining table
        public DbSet<OrderDetails> OrderDetails { get; set; }
    }

您的课程应该继承来自 DbContext 课程：

public class OrderDetailsContext: DbContext
        {
            public OrderDetailsContext(DbContextOptions<OrderDetailsContext> options) : base(options)
            { 
            }

            //defining table
            public DbSet<OrderDetails> OrderDetails { get; set; }
        }

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