Linq表达树2

最新推荐文章于 2025-09-09 20:40:49 发布

转载最新推荐文章于 2025-09-09 20:40:49 发布 · 55 阅读

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原文链接：http://www.cnblogs.com/mxy1028/archive/2008/11/09/1330262.html

文章标签：

#数据库

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);
            }
        }
    }
}