Question

我有两个表，RESTAURANT和HOURS，REST_ID是两个表之间的关键。当我到第一行代码添加HOUR时，我收到一个错误。该错误要求创建对象的实例，但Intellisence允许我调用该表引用。这是一段代码：

RESTAURANT addRest = new RESTAURANT();
    addRest.REST_NAME = r_name;
    addRest.REST_STREET1 = r_street;
    addRest.REST_PHONE = r_phone;
    addRest.REST_WEBSITE = r_web;
    addRest.REST_DESC = r_desc;
    addRest.HOUR.HOURS_SUN = h_su;
    addRest.HOUR.HOURS_MON = h_mo;
    addRest.HOUR.HOURS_TUE = h_tu;
    addRest.HOUR.HOURS_WED = h_we;
    addRest.HOUR.HOURS_THU = h_th;
    addRest.HOUR.HOURS_FRI = h_fr;
    addRest.HOUR.HOURS_SAT = h_sa;
    addRest.HOURReference.EntityKey = new EntityKey("FVTCEntities.HOURS", "HOURS", 1);
    db.AddToRESTAURANTs(addRest);
    db.SaveChanges();

Answer 1

HOUR是RESTAURANT内的包含对象。您需要在设置属性之前对其进行实例化（如典型的C＃对象）：

addRest.HOUR = new HOUR();
addRest.HOUR.HOURS_SUN = h_su;
...

Answer 2

您尚未在RESTAURANT上创建HOUR对象，因此导航属性为null。

...
addRest.REST_DESC = r_desc;
addRest.HOUR = new HOUR();
addRest.HOUR.HOURS_SUN = h_su;
...

LINQ to SQL：在多个表上插入表

2 个答案: