Linq表达树2

Code

   
     using System;
using System.Linq;
using System.Data.Linq;
using System.Data.Linq.Mapping;
using System.Linq.Expressions;
namespace KingRi.Test
{
 [Table(Name="account")]
 public class Account
 {
 [Column(Name="uname", DbType="varchar(50) NOT NULL")]
 public string Uname
 {
 get; 
 set;
 }
 [Column(Name="upass", DbType="varchar(50)")]
 public string Upass
 {
 get;
 set;
 }
 }
 public delegate void SelectDelegate<T1, T>(Account u);
 public class Client
 {
 static void Main()
 {
 DataContext ctx = new DataContext("server=.;database=t1;uid=sa;pwd=");
 Table<Account> users = ctx.GetTable<Account>();
 //IQueryable<Account> result = from u in users select u;
 IQueryable<string> result = users.Select<Account,string>(u=>u.Uname);
 /*
 ParameterExpression expression;
 IQueryable<Account> result = users.Select<Account,Account>(
 Expression.Lambda<Func<Account,Account>>(
 expression=Expression.Parameter(typeof(Account), "u"),
 new ParameterExpression[] {expression}
 )
 );
 */
 foreach(string a in result)
 {
 Console.WriteLine(a);
 }
 }
 }
}