模糊查询()包含

Repeater1.DataSource = con.Users.Where(r=>r.nick.Contains(a)).ToList();

Repeater1.DataBind();

根据开头查

Repeater1.DataSource = con.Users.Where(r => r.nick.StartsWith(a)).ToList();

Repeater1.DataBind();

根据结尾查

Repeater1.DataSource = con.Users.Where(r => r.nick.EndsWith(a)).ToList();

Repeater1.DataBind();

查询个数

IEnumerable
     
       uie = con.Users;Repeater1.DataSource = uie;Repeater1.DataBind();Num.Text = uie.Count().ToString();
     

或者

List
     
       uie = con.Users.ToList();Repeater1.DataSource = uie;Repeater1.DataBind();Num.Text = uie.Count.ToString();
     

最大值

Num.Text = con.Users.Max(r => r.code).ToString();

Repeater1.DataBind();　

最小值

Num.Text = con.Users.Min(r => r.code).ToString();

Repeater1.DataBind();　

平均值：

Num.Text = con.Users.Average(r => r.code).ToString();

Repeater1.DataBind();　

求和

Num.Text = con.Users.Sum(r => r.code).ToString();

Repeater1.DataBind();

升序

Repeater1.DataSource = con.Users.OrderBy(r=>r.code);

Repeater1.DataBind();

 

降序

Repeater1.DataSource = con.Users.OrderByDescending(r => r.code);

Repeater1.DataBind();

分页

Repeater1.DataSource = con.Users.Skip(5).Take(5);//跳过5个元素取5个元素Repeater1.DataBind();

　　实例：

<%@ Page Language="C#" AutoEventWireup="true" CodeFile="Default.aspx.cs" Inherits="_Default" %>
              
      
    
       
    
                            
                                 
         
        
        
                         
          
                               
用户名
                               
密码
                               
昵称
                               
性别
                               
民族
                               
班级
                               
生日
                               
操作
                          
                          
                                       
<%#Eval("usename") %>
                                       
<%#Eval("password") %>
                                       
<%#Eval("nick") %>
                                       
 " /> 
                                       
<%#Eval("Nationname") %>
                                       
<%#Eval("Classname") %>
                                       
<%#Eval("birthdayStr") %>
                                       
 
            
             修改
             
            
             删除
            
                                  
                                                         
        
        当前第
        页        
        
            
       
    
      

using System;using System.Collections.Generic;using System.Linq;using System.Web;using System.Web.UI;using System.Web.UI.WebControls;public partial class _Default : System.Web.UI.Page{    int count = 3;    protected void Page_Load(object sender, EventArgs e)    {        if (!IsPostBack)        {            using(Data1128DataContext con=new Data1128DataContext())            {                Repeater1.DataSource = con.Users.Take(count);                Repeater1.DataBind();            }        }        prve.Click += prve_Click;        next.Click += next_Click;    }        //上一页    void prve_Click(object sender, EventArgs e)    {        int nowpage = Convert.ToInt32(txt.Text) - 1;        if (nowpage < 1)            return;        txt.Text = nowpage.ToString();        using (Data1128DataContext con = new Data1128DataContext())        {            Repeater1.DataSource = con.Users.Skip((nowpage-1)*count).Take(count);            Repeater1.DataBind();        }    }    //下一页    void next_Click(object sender, EventArgs e)    {        using (Data1128DataContext con = new Data1128DataContext())        {        int nowpage = Convert.ToInt32(txt.Text) + 1;        int maxpage = Convert.ToInt32(Math.Ceiling((con.Users.Count() * 1.0) / count));        if (nowpage > maxpage)            return;        txt.Text = nowpage.ToString();                    Repeater1.DataSource = con.Users.Skip((nowpage - 1) * count).Take(count);            Repeater1.DataBind();        }    }}

 组合查询

//什么都不填，查全部        //根据所填的内容，查询对应的数据绑定到repeater上        using (Data1128DataContext con = new Data1128DataContext())        {            IQueryable
      
        Ui = con.Users.AsQueryable();//查询全部数据            string Nick = TextBox1.Text.Trim();            string Class = TextBox2.Text.Trim();            string Birthday = TextBox3.Text.Trim();            //判断是否需要填充查询条件            if (Nick.Length > 0)            {                Ui = Ui.Where(r => r.nick.Contains(Nick));            }            if (Class.Length > 0)            {                Ui = Ui.Where(r => r.Class1.classname.Contains(Class));            }            if (Birthday.Length > 0)            {                if (ddl.SelectedValue == "=")                    Ui = Ui.Where(r => Convert.ToDateTime(r.birthday).Year == Convert.ToInt32(Birthday));                if (ddl.SelectedValue == ">=")                    Ui = Ui.Where(r => Convert.ToDateTime(r.birthday).Year >= Convert.ToInt32(Birthday));                if (ddl.SelectedValue == "<=")                    Ui = Ui.Where(r => Convert.ToDateTime(r.birthday).Year <= Convert.ToInt32(Birthday));            }            Repeater1.DataSource = Ui;            Repeater1.DataBind();        }
      

using (Data1128DataContext con = new Data1128DataContext())        {            IQueryable
      
        Unick = con.Users.AsQueryable();            IQueryable
       
         Uclass = con.Users.AsQueryable();            IQueryable
        
          Ubir = con.Users.AsQueryable();            string Nick = TextBox1.Text.Trim();            string Class = TextBox2.Text.Trim();            string Birthday = TextBox3.Text.Trim();            if (Nick.Length > 0)            {                Unick = Unick.Where(r => r.nick.Contains(Nick));            }            if (Class.Length > 0)            {                Uclass = Uclass.Where(r => r.Class1.classname.Contains(Class));            }            if (Birthday.Length > 0)            {                if (ddl.SelectedValue == "=")                    Ubir = Ubir.Where(r => Convert.ToDateTime(r.birthday).Year == Convert.ToInt32(Birthday));                if (ddl.SelectedValue == ">=")                    Ubir = Ubir.Where(r => Convert.ToDateTime(r.birthday).Year >= Convert.ToInt32(Birthday));                if (ddl.SelectedValue == "<=")                    Ubir = Ubir.Where(r => Convert.ToDateTime(r.birthday).Year <= Convert.ToInt32(Birthday));            }            //取集合的交集            var Uall = Unick.Intersect(Uclass).Intersect(Ubir);            Repeater1.DataSource = Uall;            Repeater1.DataBind();        }
        
       
      

 集合的交集，并集，差集，补集（去重）

List
     
       ListA = new List
      
       ();List
       
         ListB = new List
        
         ();List
         
           ListResult = new List
          
           (); ListResult = ListA.Distinct().ToList();//去重ListResult = ListA.Except(ListB).ToList();//差集ListResult= ListA.Union(ListB).ToList(); //并集ListResult = ListA.Intersect(ListB).ToList();//交集