Linq的分页与组合查询的配合使用

1.首先使用Linq连接数据库，并扩展属性

 public partial class User
 {
     public string SexStr
     {
         get
         {
             string end = "<暂无>";
             if (this._Sex != null)
             {
                 end = Convert.ToBoolean(this._Sex) ? "男" : "女";
             }
             return end;
         }
     }
     public bool SexStr1
     {
         get
         {
             bool end=false;

             if (this._Sex != null)
             {
                 end = Convert.ToBoolean(this._Sex) ;
             }
             return end;
         }
     }
     public string NationName
     {
         get
         {
             return this.Nation1.NationName;
         }
     }
     public string BirStr
     {
         get
         {
             string end = "<暂无>";
             if(this._Birthday!=null)
             {
                 end = Convert.ToDateTime(this._Birthday).ToString("yyyy年MM月dd日");
             }
             return end;
         }
     }
     public int Age
     {
         get
         {
             int end=;
             if (this._Birthday != null)
             {
                 int y = DateTime.Now.Year;
                 int a = Convert.ToDateTime(this._Birthday).Year;
                 end = y-a;
             }
             return end;
         }
     }
 }

扩展属性

2.HTML代码

<form id="form1" runat="server">
        <div id="select">
            用户名：<asp:TextBox ID="TextBox1" runat="server" Width=""></asp:TextBox>
           性别：<asp:TextBox ID="tb_sex" runat="server" Width="60px"></asp:TextBox>&nbsp
            年龄：<asp:DropDownList ID="DropDownList3" runat="server">
                <asp:ListItem Selected="True" Value="&lt;=">&gt;=</asp:ListItem>
                <asp:ListItem Value="&gt;=">&lt;=</asp:ListItem>
            </asp:DropDownList><asp:TextBox ID="tb_age" runat="server" Width="60px"></asp:TextBox>
             &nbsp<asp:Button ID="Button2" CssClass="Button" runat="server" Text="查询" />&nbsp&nbsp<a href="Insert.aspx" target="_blank" class="link">添加</a></div> 

        <asp:Repeater ID="Repeater1" runat="server">
            <HeaderTemplate >
                <table style="width: 100%; background-color: #4cff00; text-align: center;">
                     <tr style="color:#ff6a00;">
                        <td>用户名</td>
                        <td>密码</td>
                        <td>昵称</td>
                        <td>性别</td>
                        <td>生日</td>
                         <td>年龄</td>
                        <td>民族</td>
                         <td>操作</td>
                    </tr>
            </HeaderTemplate>
            <ItemTemplate>
                <tr style="background-color:#0ff;" class="tr_item">
                    <td><%#Eval("UserName") %></td>
                    <td><%#Eval("PassWord") %></td>
                    <td><%#Eval("NickName") %></td>
                    <td><%#Eval("SexStr") %></td>
                    <td><%#Eval("Birthday","{0:yyyy年MM月dd日}") %></td>
                    <td><%#Eval("Age") %></td>
                    <td><%#Eval("NationName") %></td>
                    <td><a href="update.aspx?un=<%#Eval("UserName") %>" target="_blank" class="link">修改</a>&nbsp;&nbsp;
                        <a id="lian" href="delete.aspx?un=<%#Eval("UserName") %>" onclick="return del()" class="link">删除</a></td>
                </tr>
            </ItemTemplate>
            <FooterTemplate>
                </table>
            </FooterTemplate>
        </asp:Repeater>
        //隐藏域放用户输入的多条件查询内容
        <asp:HiddenField ID="HiddenField1" runat="server" />
        <asp:HiddenField ID="HiddenField2" runat="server" />
        <asp:HiddenField ID="HiddenField3" runat="server" />
         <div id="aa">当前第&nbsp<asp:Label ID="Label2" runat="server" Text="Label"></asp:Label>&nbsp页&nbsp&nbsp共&nbsp<asp:Label ID="Label3" runat="server" Text="Label"></asp:Label>&nbsp页
            <asp:Button ID="btn_first" runat="server" CssClass="ye" Text="首页" />&nbsp<asp:Button ID="btn_prev" runat="server" Text="上一页" CssClass="ye" />&nbsp<asp:Button ID="btn_next" runat="server" Text="下一页" CssClass="ye" />&nbsp<asp:Button ID="btn_end" runat="server" Text="末页" CssClass="ye"/>
            <asp:DropDownList ID="DropDownList2" runat="server" AutoPostBack="True"></asp:DropDownList></div>
    </form>

3、C#功能实现

 private IEnumerable<global::User> sel(WebDataContext con)
     {
         var All = con.User.AsEnumerable();
         if (HiddenField1.Value.Length > )
         {
             var namelist = con.User.Where(r => r.UserName.Contains(TextBox1.Text.Trim()));

             All = All.Intersect(namelist);
         }

         if (HiddenField2.Value == "男" || HiddenField2.Value == "女")
         {
             var sexlist = con.User.Where(r => Convert.ToBoolean(r.Sex) == (tb_sex.Text.Trim() == "男" ? true : false));

             All = All.Intersect(sexlist);
         }

         if (HiddenField3.Value.Length > )
         {
             int nowyear = DateTime.Now.Year;
             try
             {
                 int age = Convert.ToInt32(tb_age.Text.Trim());
                 int g = nowyear - age;
                 DateTime d = Convert.ToDateTime(g.ToString() + "-1-1");
                 if (DropDownList3.SelectedValue == ">=")
                 {
                     var agelist = con.User.Where(r => Convert.ToDateTime(r.Birthday) >= d);
                     All = All.Intersect(agelist);

                 }
                 else
                 {
                     DateTime dd = Convert.ToDateTime(g.ToString() + "-12-31");
                     var agelist = con.User.Where(r => Convert.ToDateTime(r.Birthday) <= dd);
                     All = All.Intersect(agelist);

                 }
             }
             catch
             {
             }
         }
         return All;
     }

查询方法

 int Pagecount = ;
     protected void Page_Load(object sender, EventArgs e)
     {
         if (!IsPostBack)
         {
             using (WebDataContext con = new WebDataContext())
             {
                 var All = sel(con);
                 Repeater1.DataSource = All.Take(Pagecount).ToList();
                 Repeater1.DataBind();
             }
             Label2.Text = "";//当前页
             Label3.Text = MaxPageNumber().ToString();
             for (int i = ; i <= MaxPageNumber();i++ )
             {
                 DropDownList2.Items.Add(new ListItem(i.ToString(), i.ToString()));
             }
         }

     }

初加载

 void Button2_Click(object sender, EventArgs e)//查询按钮
     {
         HiddenField1.Value = TextBox1.Text.Trim();
         HiddenField2.Value = tb_sex.Text.Trim();
         HiddenField3.Value = tb_age.Text.Trim();
         using (WebDataContext con = new WebDataContext())
         {
             var All = sel(con);
             Repeater1.DataSource = All.Take(Pagecount).ToList();
             Repeater1.DataBind();
             Label2.Text = "";
             Label3.Text = MaxPageNumber().ToString();
             DropDownList2.Items.Clear();
             for (int i = ; i <= MaxPageNumber(); i++)
             {
                 DropDownList2.Items.Add(new ListItem(i.ToString(), i.ToString()));
             }
     }
     }

查询按钮点击

 void DropDownList2_SelectedIndexChanged(object sender, EventArgs e)
     {
         using (WebDataContext con = new WebDataContext())
         {
             var All = sel(con);
             Repeater1.DataSource = All.Skip(Pagecount * (Convert.ToInt32(DropDownList2.SelectedValue) - )).Take(Pagecount).ToList();
             Repeater1.DataBind();
         }
         Label2.Text =DropDownList2.SelectedValue;    }

快捷跳转

 void btn_first_Click(object sender, EventArgs e)
     {
         using (WebDataContext con = new WebDataContext())
         {
             var All = sel(con);
             Repeater1.DataSource = All.Take(Pagecount).ToList();
             Repeater1.DataBind();
         }
         Label2.Text ="";
         DropDownList2.SelectedValue = "";
     }

首页

 void btn_end_Click(object sender, EventArgs e)
     {
         using (WebDataContext con = new WebDataContext())
         {
             var All = sel(con);
             Repeater1.DataSource = All.Skip(Pagecount * (Convert.ToInt32(Label3.Text) - )).Take(Pagecount).ToList();
             Repeater1.DataBind();
         }
         Label2.Text = Label3.Text;
         DropDownList2.SelectedValue = Label3.Text;
     }

末页

 void btn_prev_Click(object sender, EventArgs e)
     {
         int NowNumber = Convert.ToInt32(Label2.Text) -;
         if (NowNumber <)
         {
             return;
         }
         using (WebDataContext con = new WebDataContext())
         {
             var All = sel(con);
             Repeater1.DataSource = All.Skip(Pagecount * (NowNumber - )).Take(Pagecount).ToList();
             Repeater1.DataBind();
         }

         Label2.Text = NowNumber.ToString();
         DropDownList2.SelectedValue = NowNumber.ToString();
     }

上一页

 void btn_next_Click(object sender, EventArgs e)
     {
         int NowNumber = Convert.ToInt32(Label2.Text) + ;
         if (NowNumber > Convert.ToInt32(Label3.Text))
         {
             return;
         }
         using (WebDataContext con = new WebDataContext())
         {
             var All = sel(con);
             Repeater1.DataSource = All.Skip(Pagecount * (NowNumber - )).Take(Pagecount).ToList();
             Repeater1.DataBind();
         }

         Label2.Text = NowNumber.ToString();
         DropDownList2.SelectedValue = NowNumber.ToString();

     }

下一页

 public int MaxPageNumber()
     {
         using (WebDataContext con = new WebDataContext())
         {
             var All = sel(con);
             double nu = All.ToList().Count / (Pagecount * 1.0);
             int num = Convert.ToInt32(Math.Ceiling(nu));
             return num;
         }
     }

计算总页数