[已解决问题] 求自然连接查询Sql语句的Linq表达式！
提问时间: 2008-03-28 08:41
悬赏分：10 浏览:596 次
（1）select A.a,B.b
from t1 as A,t2 as B
where A.ID=B.ID ;
(2) delete from t1 as A, t2 as B
where A.ID=B.ID ; (要表达的意思是：如果从用户表中删除用户信息则把他在评论表中的评论也全部删除)
谢谢
最佳答案
var q = from a in db.Customers
from b in db.Employees
where a.City == b.City
select new
{
a.City,
b.Address
};
SELECT [t0].[City], [t1].[Address]
FROM [dbo].[Customers] AS [t0], [dbo].[Employees] AS [t1]
WHERE [t0].[City] = [t1].[City]
对于多表删除好像是一对多关系，参看这个：
Order与OrderDetail是一对多关系，首先DeleteOnSubmit其OrderDetail(多端)，其次DeleteOnSubmit其Order(一端)。因为一端是主键。
var orderDetails =
from o in db.OrderDetails
where o.Order.CustomerID == "WARTH" && o.Order.EmployeeID == 3
select o;
var order =
(from o in db.Orders
where o.CustomerID == "WARTH" && o.EmployeeID == 3
select o).First();
foreach (OrderDetail od in orderDetails)
{
db.OrderDetails.DeleteOnSubmit(od);
}
db.Orders.DeleteOnSubmit(order);
db.SubmitChanges();
提问者对于答案的评价：3q
from b in db.Employees
where a.City == b.City
select new
{
a.City,
b.Address
};
SELECT [t0].[City], [t1].[Address]
FROM [dbo].[Customers] AS [t0], [dbo].[Employees] AS [t1]
WHERE [t0].[City] = [t1].[City]
对于多表删除好像是一对多关系，参看这个：
Order与OrderDetail是一对多关系，首先DeleteOnSubmit其OrderDetail(多端)，其次DeleteOnSubmit其Order(一端)。因为一端是主键。
var orderDetails =
from o in db.OrderDetails
where o.Order.CustomerID == "WARTH" && o.Order.EmployeeID == 3
select o;
var order =
(from o in db.Orders
where o.CustomerID == "WARTH" && o.EmployeeID == 3
select o).First();
foreach (OrderDetail od in orderDetails)
{
db.OrderDetails.DeleteOnSubmit(od);
}
db.Orders.DeleteOnSubmit(order);
db.SubmitChanges();
2008/3/29 10:27:02
回答者：李永京
提问者对于答案的评价：3q
其它回答(3)
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晕 要代码啊
不知道自己去网上搜吗? 你在用之前 先好好学习好 MSDN 上面都有的 linq sql 看了李兄的回答还是一知半解，还是先看看语法去 Product pro = db.Products.Single(b => b.Category.CategoryName == categoryName); db.Products.DeleteOnSubmit(pro); db.SubmitChanges(); 这里例子是我用来删除报表里面名为categoryName的Category条目时候，同时把Products表中的记录删除，我不知道你的数据库的具体东西，按照这样的方法删除吧 （不过得先建立外键关系） 括号里面的是LAMBDA表达式 |
评论
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3个月前 Kevin Li : 看来研究得人不多，算了，还是用传统得sql |