1.新建一个winform项目。
2.添加一个Linq to Sql 类，命名为Northwind
3.打开服务器资源管理器，将表拖动到linq to sql 类，实体类就由Vs生成了
4.实例化DataContext类
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1
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NorthwindDataContext dc = new
NorthwindDataContext();
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5.下面就可以使用Linq to Sql啦。
a.查询Employees所有数据
var ee =
from employee in dc.Employees
select employee;
b.加个Where条件，查询Employee表所有City=London
var e2 = from employee in dc.Employees where employee.City == "London" select employee;
c.查询EmployeeID<5的数据
var e3 = from employee in dc.Employees where employee.EmployeeID < 5 select employee;
d.查询雇佣日期在1993年1月1日以前的人员。
var e4 = from employee in dc.Employees where employee.HireDate < new DateTime(1993, 1, 1) select employee;
e.多个查询条件
var e5 = from employee in dc.Employees where employee.HireDate < new DateTime(1993, 1, 1) where employee.EmployeeID < 3 select employee;
f.like语句
var e6 = from employee in dc.Employees where SqlMethods.Like(employee.FirstName, "%a%") //where employee.FirstName.Contains("a") //等价于 like ‘%a%‘ //where employee.FirstName.StartsWith("a") //等价于 like ‘a%‘ //where employee.FirstName.EndsWith("a") //等价于 like ‘%a‘ select employee;
g.查询指定的列
var e7 = (from employee in dc.Employees //select new { employee.EmployeeID, employee.FirstName }; select new { 员工编号 = employee.EmployeeID, 员工姓名 = employee.FirstName, 尊称 = employee.TitleOfCourtesy });
h.子查询
var e8 = from employee in dc.Employees where employee.Orders.Count > 100 select employee;
i.内连接
/** * 查询位于伦敦的客户的订单 * SELECT * * FROM [dbo].[Orders] * INNER JOIN [dbo].[Customers] ON [Customers].[CustomerID] = [Orders].[CustomerID] * WHERE [Customers].[City] = ‘London‘ */ var e9 = from cus in dc.Customers join ord in dc.Orders on cus.CustomerID equals ord.CustomerID where cus.City == "London" select ord;
j.增加
Employees m = new Employees(); m.LastName = "闪硕"; m.FirstName = "燕"; m.Title = "闪硕标题"; dc.Employees.InsertOnSubmit(m); dc.SubmitChanges();
k.修改
var e10 = dc.Employees.FirstOrDefault(employee => employee.LastName == "闪硕"); e10.City = "石家庄"; dc.SubmitChanges();
l.删除
var e10 = dc.Employees.FirstOrDefault(employee => employee.LastName == "闪硕"); dc.Employees.DeleteOnSubmit(e10); dc.SubmitChanges();
练习代码使用Vs2012，微软northwnd示例数据库
代码下载：http://pan.baidu.com/s/1pJyh0Mn