一、linq高级查
1.模糊查（字符串包含）
public List<User> Select(string name)
{
return con.User.Where(r =>
r.UserName.Contains(name)).ToList();
}
2.查开头（StartsWith,以XX开头）
public List<User> Select(string name)
{
return con.User.Where(r => r.UserName.StartsWith(name)).ToList();
}
3.查结尾
public List<User> Select(string name)
{
return con.User.Where(r => r.UserName.EndsWith(name)).ToList();
}
4.查出来的数组长度（个数）
clist.Count()
5.最大值：Max(r => r.price);
public decimal? SelectMax()
{
return con.car.Max(r => r.price);
}
6.最小值：Min(r => r.price);
public decimal? SelectMin()
{
return con.car.Min(r => r.price);
}
7.平均值：Average(r => r.price);
public decimal? SelectAvg()
{
return con.car.Average(r => r.price);
}
8.求和：Sum(r => r.price);
public decimal? SelectSum() { return con.car.Sum(r => r.price); }
9.排序：
1、OrderBy 按升序对值进行排序。
2、OrderByDescending 按降序对值进行排序
3、ThenBy 按升序执行次要排序。
4、ThenByDescending 按降序执行次要排序。
（1）升序：OrderBy(r => r.price)
public List<car> orderBy()
{
return con.car.OrderBy(r => r.price).ToList();
}
（2）降序：OrderByDescending(r => r.price)
public List<car> orderBy()
{ return con.car.OrderByDescending(r => r.oil).ToList();
}
二、分页与组合查询
<%@ Page Language="C#" AutoEventWireup="true" CodeFile="Default.aspx.cs" Inherits="_Default" %> <!DOCTYPE html> <html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title></title>
<style>
.image {
width: 30px;
height: 30px;
position: relative;
float: left;
margin-top: 5px;
} .caozuo {
position: relative;
float: left;
margin-left: 50px;
margin-top: 12px;
width: 50px;
height: 30px; }
</style>
</head>
<body>
<form id="form1" runat="server">
<div>
昵称：<asp:TextBox ID="TextBox1" runat="server"></asp:TextBox>
性别：<asp:TextBox ID="TextBox2" runat="server"></asp:TextBox>
年龄：<select id="DropDownList1" runat="server">
<option>>=</option>
<option><</option>
</select>
<asp:TextBox ID="TextBox3" runat="server"></asp:TextBox>
<asp:Button ID="Button1" runat="server" Text="查询" /><br />
<br /> <asp:Repeater ID="Repeater1" runat="server">
<HeaderTemplate>
<table style="width: 100%; text-align: center; background-image: url(images/2.jpg);">
<tr style="color: red; height: 45px; font-size: 24px;">
<td>编号</td>
<td>用户名</td>
<td>密码</td>
<td>昵称</td>
<td>性别</td>
<td>生日</td>
<td>民族</td>
<td>班级</td>
<td style="text-align: left; width: 180px;">
<div class="caozuo">操作</div>
<div class="image">
<a href="Insert.aspx" target="_blank">
<img src="data:images/4.png" height="" width="" /></a>
</div>
</td>
</HeaderTemplate>
<ItemTemplate>
<tr class="t" style="background-color: white;">
<td><%#Eval("ids") %></td>
<td><%#Eval("UserName") %></td>
<td><%#Eval("PassWord") %></td>
<td><%#Eval("NickName") %></td>
<td> <img src="<%#Eval("SexStr") %>" /> </td>
<td><%#Eval("Birthday","{0:yyyy年MM月dd日}") %></td>
<td><%#Eval("NationName") %></td>
<td><%#Eval("ClassName") %></td>
<td>
<a href="Delete.aspx?i=<%#Eval("UserName") %>">删除</a>
<a href="Update.aspx?i=<%#Eval("UserName") %>">修改</a>
</td>
</tr>
</ItemTemplate>
<FooterTemplate>
</table>
</FooterTemplate>
</asp:Repeater>
<div style="width: 800px; height: 20px; margin: auto">
当前第【<asp:Label ID="Label" runat="server" Text="Label"></asp:Label>】页
共【<asp:Label ID="Labe2" runat="server" Text="Label"></asp:Label>】页
<asp:LinkButton ID="btn_prev" runat="server" CssClass="wenzi">上一页</asp:LinkButton>
<asp:LinkButton ID="btn_next" runat="server" CssClass="wenzi">下一页</asp:LinkButton>
</div>
</div>
</form>
</body>
</html>
<script>
var ts = document.getElementsByClassName("t");
for (var i = ; i < ts.length; i++) {
ts[i].onmouseover = function () {
if (this.style.backgroundColor == "white")
this.style.backgroundColor = "yellow";
}; ts[i].onmouseout = function () {
if (this.style.backgroundColor == "yellow") {
this.style.backgroundColor = "white";
}
}; ts[i].onclick = function () {
for (var j = ; j < ts.length; j++) {
ts[j].style.backgroundColor = "white";
}
var colorArr = ["", "", "", "", "", "", "", "", "", "", "A", "B", "C", "D", "E", "F"];
var colorVal = "#";
for (i = ; i < ; i++) {
colorVal += colorArr[Math.round( * Math.random())];
}
alert(colorVal)
this.style.backgroundColor= colorVal;
};
}
</script> aspx
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 number = ;
int count=;
protected void Page_Load(object sender, EventArgs e)
{
if (!IsPostBack)
{
Label.Text = "";
using (Data0928DataContext con = new Data0928DataContext())
{
double zong=Math.Ceiling(con.Users.ToList().Count/(count*1.0));
Labe2.Text=zong.ToString();
Repeater1.DataSource= con.Users.Skip(count * (number - )).Take(count).ToList();
Repeater1.DataBind();
}
} Button1.Click += Button1_Click;
btn_next.Click += btn_next_Click;
btn_prev.Click += btn_prev_Click;
}
//上一页
void btn_prev_Click(object sender, EventArgs e)
{
int nu = Convert.ToInt32(Label.Text) - ;
Label.Text = nu.ToString();
if (nu < )
{
nu = ;
Label.Text = "";
return;} chaxun();
}
//下一页
void btn_next_Click(object sender, EventArgs e)
{
int nu = Convert.ToInt32(Label.Text) + ;
Label.Text = nu.ToString();
if (nu > Convert.ToInt32(Labe2.Text))
{
nu = Convert.ToInt32(Labe2.Text.Trim());
Label.Text = Labe2.Text.Trim();
return;
}
chaxun();
}
//查询
void Button1_Click(object sender, EventArgs e)
{
chaxun();
}
//查询方法
private void chaxun()
{
using (Data0928DataContext con = new Data0928DataContext())
{
var All = con.Users.AsQueryable();//AsEnumerale也是一个集合，不会占用系统空间，相当于只是把查询字符串给拼接起来，准备好，当执行ToList时才会进行查询
if (TextBox1.Text.Trim().Length > )//说明这里填写了内容
{
var namelist = con.Users.Where(r => r.NickName.Contains(TextBox1.Text.Trim())); All = All.Intersect(namelist);
} if (TextBox2.Text.Trim() == "男" || TextBox2.Text.Trim() == "女")
{
var sexlist = con.Users.Where(r => Convert.ToBoolean(r.Sex) == (TextBox2.Text.Trim() == "男" ? true : false)); All = All.Intersect(sexlist);
} if (TextBox3.Text.Trim().Length > )
{
int nowyear = DateTime.Now.Year;
try
{
int age = Convert.ToInt32(TextBox3.Text.Trim());
int g = nowyear - age;
DateTime d = Convert.ToDateTime(g.ToString() + "-1-1");
if (DropDownList1.SelectedIndex == )
{
var agelist = con.Users.Where(r => Convert.ToDateTime(r.Birthday) >= d);
All = All.Intersect(agelist); }
else
{
DateTime dd = Convert.ToDateTime(g.ToString() + "-12-31");
var agelist = con.Users.Where(r => Convert.ToDateTime(r.Birthday) <= dd);
All = All.Intersect(agelist); }
}
catch
{
}
}
double zong = Math.Ceiling(All.ToList().Count / (count * 1.0));//取上限
Labe2.Text = zong.ToString();
Repeater1.DataSource = All.Skip((Convert.ToInt32(Label.Text.Trim())-)*count).Take(count);
Repeater1.DataBind();
}
}
} aspx.cs