我在 .Net 4 上使用 EF 5
我有以下模型:
public class Order
{
[Key]
public int Id { get; set; }
public string OrderId { get; set; }
public Address BillingAddress { get; set; }
public Address DeliveryAddress { get; set; }
public ICollection<OrderLine> OrderLines { get; set; }
}
public class OrderLine
{
[Key]
public int Id { get; set; }
public string Description { get; set; }
public decimal UnitPrice { get; set; }
public int Quantity { get; set; }
public string SKU { get; set; }
public decimal ShippingCost { get; set; }
public decimal Tax { get; set; }
}
public class Address
{
[Key]
public int Id { get; set; }
public string Addressee { get; set; }
public string AddressLine1 { get; set; }
public string AddressLine2 { get; set; }
public string AddressLine3 { get; set; }
public string Town { get; set; }
public string County { get; set; }
public string Country { get; set; }
public string Postcode { get; set; }
}
和模型配置:
protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
modelBuilder.Entity<Order>().HasMany(x => x.OrderLines).WithRequired().WillCascadeOnDelete();
modelBuilder.Entity<Order>().HasOptional(x => x.BillingAddress).WithOptionalDependent().WillCascadeOnDelete();
modelBuilder.Entity<Order>().HasOptional(x => x.DeliveryAddress).WithOptionalDependent().WillCascadeOnDelete();
base.OnModelCreating(modelBuilder);
}
当我运行以下查询时,我得到带有 19 个连接 的 sql,这对于简单的关系来说似乎过多了
context.Orders
.Where(x => x.OrderId == orderId)
.Include(x => x.OrderLines)
.Include(x => x.BillingAddress)
.Include(x => x.DeliveryAddress)
.FirstOrDefault();
我做错了什么吗?是否有不同的格式来优化生成的 SQL 的 linq 查询?
编辑:
最佳答案
我认为问题出在帐单地址和送货地址上的 WithOptionalDependent
上。这在地址和订单之间创建了 1:1 的关系,即使表是为 1:many 关系设置的。
如果您更改配置以改为使用 WithMany
:
protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
modelBuilder.Entity<Order>().HasMany(x => x.OrderLines).WithRequired().WillCascadeOnDelete();
modelBuilder.Entity<Order>().HasOptional(x => x.BillingAddress).WithMany().WillCascadeOnDelete();
modelBuilder.Entity<Order>().HasOptional(x => x.DeliveryAddress).WithMany().WillCascadeOnDelete();
base.OnModelCreating(modelBuilder);
}
查询要简单得多,本质上等同于:
...
FROM [Orders]
LEFT OUTER JOIN [Addresses] As B ON [Orders].[BillingAddress_Id] = B.[Id]
LEFT OUTER JOIN [Addresses] As D ON [Orders].[DeliveryAddress_Id] = D.[Id]
LEFT OUTER JOIN [OrderLines] ON [Orders].[Id] = [OrderLines].[Order_Id]
关于c# - 如何使用 3 includes 优化 Entity Framework 查询,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/13864675/