实体框架不会创建数据库

Question

我尝试实现Entity Framework Code First方法。我有两个课程Student和Standard（成绩）。这是我的标准型号：

class Standard
    {
        public Standard()
        {

        }
        public int StandardId { get; set; }
        public string StandardName { get; set; }

        public ICollection<Student> Students { get; set; }
    }

和学生模特：

class Student
    {
        public Student()
        {

        }
        public int StudentID { get; set; }
        public string StudentName { get; set; }
        public DateTime? DateOfBirth { get; set; }
        public byte[] Photo { get; set; }
        public decimal Height { get; set; }
        public float Weight { get; set; }

        public Standard Standard { get; set; }
    }

上下文：

class SchoolContext : DbContext
{
    public SchoolContext() : base()
    {

    }

    public DbSet<Student> Students { get; set; }
    public DbSet<Standard> Standards { get; set; }
}

App config：

    <?xml version="1.0" encoding="utf-8"?>
<configuration>
  <configSections>
    <!-- For more information on Entity Framework configuration, visit http://go.microsoft.com/fwlink/?LinkID=237468 -->
    <section name="entityFramework" type="System.Data.Entity.Internal.ConfigFile.EntityFrameworkSection, EntityFramework, Version=6.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" requirePermission="false" />
  </configSections>
  <startup>
    <supportedRuntime version="v4.0" sku=".NETFramework,Version=v4.5.2" />
  </startup>
  <entityFramework>
    <defaultConnectionFactory type="System.Data.Entity.Infrastructure.LocalDbConnectionFactory, EntityFramework">
      <parameters>
        <parameter value="(LocalDb)\MSSQLLocalDB" />
      </parameters>
    </defaultConnectionFactory>
    <providers>
      <provider invariantName="System.Data.SqlClient" type="System.Data.Entity.SqlServer.SqlProviderServices, EntityFramework.SqlServer" />
    </providers>
  </entityFramework>
</configuration>

和主要方法：

class Program
{
    static void Main(string[] args)
    {
        using (var ctx = new SchoolContext())
        {
            ctx.Database.Initialize(force:true);

            Student stud = new Student() { StudentName = "New Student" };

            ctx.Students.Add(stud);
            ctx.SaveChanges();
        }
    }
}

它编译并运行但数据库不存在。我哪里弄错了？