【2017-5-24】WebForm 条件查询

实体类

    public int ids { get; set; }
    public string code { get; set; }
    public string name { get; set; }
    public decimal oil { get; set; }
    public decimal price { get; set; }

封装类

注意引用using System.Data.SqlClient;

SqlConnection conn = null;
    SqlCommand cmd = null;

    public carData()
    {
        conn = new SqlConnection("server=.;database=One;user=sa;pwd=123");
        cmd = conn.CreateCommand();
    }

    //查询全部
    public List<car> SelectAll()
    {
        List<car> clist = new List<car>();
        cmd.CommandText = "select * from car";
        conn.Open();
        SqlDataReader dr = cmd.ExecuteReader();
        if (dr.HasRows)
        {
            while (dr.Read())
            {
                car c = new car();
                c.ids = Convert.ToInt32(dr["ids"]);
                c.code = dr["code"].ToString();
                c.name = dr["name"].ToString();
                c.oil = Convert.ToDecimal(dr["oil"]);
                c.price = Convert.ToDecimal(dr["price"]);
                clist.Add(c);
            }
        }
        conn.Close();
        return clist;
    }

    //分页查询
    public List<car> SelectAll(int count, int number)
    {
        List<car> clist = new List<car>();
        cmd.CommandText = "select top " + count + " * from car where ids not in(select top " + (count * (number - 1)) + " ids from car)";
        conn.Open();
        SqlDataReader dr = cmd.ExecuteReader();
        if (dr.HasRows)
        {
            while (dr.Read())
            {
                car c = new car();
                c.ids = Convert.ToInt32(dr["ids"]);
                c.code = dr["code"].ToString();
                c.name = dr["name"].ToString();
                c.oil = Convert.ToDecimal(dr["oil"]);
                c.price = Convert.ToDecimal(dr["price"]);
                clist.Add(c);
            }
        }
        conn.Close();
        return clist;
    }

    //查询数据条数
    public int SelectCount()
    {
        int a = 0;
        cmd.CommandText = "select count(*) from car";
        conn.Open();
        SqlDataReader dr = cmd.ExecuteReader();
        dr.Read();
        a = Convert.ToInt32(dr[0]);
        conn.Close();
        return a;
    }

    //条件查询
    public List<car> SelectAll(string tsql, Hashtable hs)
    {
        List<car> clist = new List<car>();
        cmd.CommandText = tsql;
        cmd.Parameters.Clear();
        foreach(string h in hs.Keys)
        {
        cmd.Parameters.AddWithValue(h,hs[h]);
        }
        conn.Open();
        SqlDataReader dr = cmd.ExecuteReader();
        if (dr.HasRows)
        {
            while (dr.Read())
            {
                car c = new car();
                c.ids = Convert.ToInt32(dr["ids"]);
                c.code = dr["code"].ToString();
                c.name = dr["name"].ToString();
                c.oil = Convert.ToDecimal(dr["oil"]);
                c.price = Convert.ToDecimal(dr["price"]);
                clist.Add(c);
            }
        }
        conn.Close();
        return clist;
    }

前端

名称：<asp:TextBox ID="TextBox1" runat="server"></asp:TextBox>
        油耗：<asp:DropDownList ID="DropDownList1" runat="server">
            <asp:ListItem Text="小于" Value="<"></asp:ListItem>
            <asp:ListItem Text="小于等于" Value="<="></asp:ListItem>
            <asp:ListItem Text="等于" Value="="></asp:ListItem>
            <asp:ListItem Text="大于等于" Value=">="></asp:ListItem>
            <asp:ListItem Text="大于" Value=">"></asp:ListItem>
        </asp:DropDownList>
        <asp:TextBox ID="TextBox2" runat="server"></asp:TextBox>
        价格：<asp:DropDownList ID="DropDownList2" runat="server">
            <asp:ListItem text="任意金额" Value="null"></asp:ListItem>
            <asp:ListItem text="小于30万" Value="price < 30"></asp:ListItem>
            <asp:ListItem text="大于30万小于40万" Value="price > 30 and price < 40"></asp:ListItem>
            <asp:ListItem text="大于40万小于50万" Value="price > 40 and price < 50"></asp:ListItem>
            <asp:ListItem text="大于50万" Value="price > 40"></asp:ListItem>
           </asp:DropDownList>
        &nbsp;&nbsp;&nbsp;&nbsp;

        <asp:Button ID="Button1" runat="server" Text="查询" />

        <br />
        <br />
        <br />
        <br />
        <br />
        <br />
        <table style="width: 100%; background-color: #0094ff; text-align: center;">
            <tr>
                <td>Ids</td>
                <td>编号</td>
                <td>名称</td>
                <td>油耗</td>
                <td>价格</td>
            </tr>

            <asp:Repeater ID="Repeater1" runat="server">
                <ItemTemplate>
                    <tr style="background-color: #fff;">
                        <td><%#Eval("ids") %></td>
                        <td><%#Eval("code") %></td>
                        <td><%#Eval("name") %></td>
                        <td><%#Eval("oil") %></td>
                        <td><%#Eval("price") %></td>
                    </tr>
                </ItemTemplate>
            </asp:Repeater>
        </table>

后台

if (!IsPostBack)
        {
            Repeater1.DataSource = new carData().SelectAll();
            Repeater1.DataBind();
        }
        //查询按钮
        Button1.Click += Button1_Click;
    }

    void Button1_Click(object sender, EventArgs e)
    {
        //防止字符串注入攻击，将用户自己输得内容放到哈希表集合当中
        Hashtable hs = new Hashtable();
        int count = 0;
        string tsql = "select * from car ";
        if (TextBox1.Text.Trim().Length > 0)
        {
            tsql += "where name like @a ";
            hs.Add("@a", "%" + TextBox1.Text.Trim() + "%");
            count++;
        }
        if (TextBox2.Text.Trim().Length > 0)
        {
            if (count > 0)
            {
                tsql += "and oil " + DropDownList1.SelectedValue + " @b ";
            }
            else
            {
                tsql += "where oil " + DropDownList1.SelectedValue + " @b ";
            }
            hs.Add("@b", "TextBox2.Text.Trim()");
            count++;
        }
        if (DropDownList2.SelectedValue != "null")
        {
            if (count > 0)
            {
                tsql += "and " + DropDownList2.SelectedValue;
            }
            else
            {
                tsql += "where " + DropDownList2.SelectedValue;
            }
            count++;
        }
        //数据绑定
        Repeater1.DataSource = new carData().SelectAll(tsql,hs);
        Repeater1.DataBind();
    }