linq - 无法转换为 system.guid

Question

我们正在使用 Entity Framework

---

private t_Market getMarketByCellsiteID(Guid cellsiteID)
{
    try
    {
        t_Market market = null;
        using (LiveLeaseEntities Entities = new LiveLeaseEntities())
        {
            market = (from m in Entities.t_Market
                      where m.OperatorId = (from o in Entities.t_CellSite
                                            where o.CellSiteId == Guid.Parse("53B7B160-20C4-4B60-948A-06570E6E3CBA")
                                            select o.OperatorId)
                      select m).Single();
            return market;
        }
    }

---

我得到无法将类型“System.Linq.IQueryable”隐式转换为“System.Guid”

Answer 1

我认为这应该可以解决:

private t_Market getMarketByCellsiteID(Guid cellsiteID)
{
try
{
    t_Market market = null;
    using (LiveLeaseEntities Entities = new LiveLeaseEntities())
    {
        market = (from m in Entities.t_Market
                  where m.OperatorId == (from o in Entities.t_CellSite
                                        where o.CellSiteId == Guid.Parse("53B7B160-20C4-4B60-948A-06570E6E3CBA")
                                        select o.OperatorId).Single()
                  select m).Single();
        return market;
    }
}

两件事:您需要一个 == 来与 m.OperatorId 进行比较，并且您正在将它与返回 IQuerable 的 LINQ 查询进行比较——调用LINQ 查询上的 Single() 执行它并返回一个值进行比较。