1、组合查询
(1)数据访问类
//参数1：SQL语句 参数2：哈希表public List<Users> chas(string s,Hashtable has)
{
List<Users> List = new List<Users>();
Users u = null;
com.CommandText = s;
com.Parameters.Clear();
foreach(string aa in has.Keys)
{
com.Parameters.Add(aa,has[aa]);
}
con.Open();
SqlDataReader dr = com.ExecuteReader();
if (dr.HasRows)
{
while (dr.Read())
{
u = new Users()
{
UserName = dr[0].ToString(),
PassWord = dr[1].ToString(),
NickName = dr[2].ToString(),
Sex = Convert.ToBoolean(dr[3]),
Birthday = Convert.ToDateTime(dr[4]),
Phone = dr[5].ToString(),
Email = dr[6].ToString(),
Natoin = dr[7].ToString(),
Area = dr[8].ToString(),
};
List.Add(u);
}
}
con.Close();
return List;
}
（2）查找按钮事件
Hashtable has = new Hashtable();//实例化哈希表，作用防攻击
//拼sql语句
string sqls = "select *from Users ";
if(TextBox1.Text!="")
{
sqls += " where UserName like @a";
has.Add("@a", "%" + TextBox1.Text.Trim() + "%");//将用户输入的内容放进哈希表，防攻击
count++;
}
if(Drop_nation.SelectedValue !="0")
{
if(count !=0)//如果上面有查询条件接and
{
sqls += " and [email protected]";
}
else//如果上面没有查询条件接where
{
sqls += " WHERE [email protected]";
count++;
}
string sss=Drop_nation.SelectedValue.ToString();
has.Add("@b",sss );
count++;
}
//Repeater数据绑定
Repeater1.DataSource = new Usersdata().chas(sqls,has);
Repeater1.DataBind();
count = 0;
2、分页
前台
当前第<asp:Label ID="Label1" runat="server" Text=""></asp:Label>页
共<asp:Label ID="Label2" runat="server" Text=""></asp:Label>页
<asp:LinkButton ID="LinkButton1" runat="server" >首页</asp:LinkButton>
<asp:LinkButton ID="LinkButton2" runat="server">上一页</asp:LinkButton>
<asp:LinkButton ID="LinkButton3" runat="server">下一页</asp:LinkButton>
<asp:LinkButton ID="LinkButton4" runat="server">末页</asp:LinkButton>
跳到
<asp:DropDownList ID="DropDownList1" AutoPostBack="true" runat="server"></asp:DropDownList>
页
后台
（1）数据访问类
//参数1：第几页 参数2：每页显示的个数public List<Users> cha(int page,int pagecode)
{
List<Users> List = new List<Users>();
Users u = null;//注意：sql语句
com.CommandText = "select top " + pagecode + " *FROM Users where UserName not in (select top " + ((page - 1) * pagecode) + " UserName FROM Users)";
con.Open();
SqlDataReader dr = com.ExecuteReader();
if (dr.HasRows)
{
while (dr.Read())
{
u = new Users()
{
UserName = dr[0].ToString(),
PassWord = dr[1].ToString(),
NickName = dr[2].ToString(),
Sex = Convert.ToBoolean(dr[3]),
Birthday = Convert.ToDateTime(dr[4]),
Phone = dr[5].ToString(),
Email = dr[6].ToString(),
Natoin = dr[7].ToString(),
Area = dr[8].ToString(),
};
List.Add(u);
}
}
con.Close();
return List;
}
（2）
//全局变量，每页显示的个数int pagecode = 5;
//跳到指定页数
void DropDownList1_SelectedIndexChanged(object sender, EventArgs e)
{
int a=Convert.ToInt32(DropDownList1.SelectedValue);//获取页数 //显示数据
Repeater1.DataSource = new Usersdata().cha(a, pagecode);
Repeater1.DataBind();
Label1.Text = a.ToString();//显示当前页
}
//下一页
void LinkButton3_Click(object sender, EventArgs e)
{
Label1.Text = (Convert.ToInt32(Label1.Text) + 1).ToString();//显示下一页
if (Convert.ToInt32(Label1.Text) <= MAXPAGE(pagecode))//判断是否小于最大页
{
Repeater1.DataSource = new Usersdata().cha(Convert.ToInt32(Label1.Text), pagecode);
Repeater1.DataBind();
}
else
{
Label1.Text = MAXPAGE(pagecode).ToString();
return;
}
}
//上一页
void LinkButton2_Click(object sender, EventArgs e)
{
Label1.Text =(Convert.ToInt32(Label1.Text) - 1).ToString();//显示上一页
if (Convert.ToInt32(Label1.Text)<=0)//判断是否大于0页
{
Label1.Text = "1";
return;
}
Repeater1.DataSource = new Usersdata().cha(Convert.ToInt32(Label1.Text), pagecode);
Repeater1.DataBind();
}
//末页
void LinkButton4_Click(object sender, EventArgs e)
{
Repeater1.DataSource = new Usersdata().cha(MAXPAGE(pagecode), pagecode);
Repeater1.DataBind();
Label1.Text = MAXPAGE(pagecode).ToString();
}
//首页
void LinkButton1_Click(object sender, EventArgs e)
{
Repeater1.DataSource = new Usersdata().cha(1, pagecode);
Repeater1.DataBind();
Label1.Text = "1";
}
//最大页数
private static int MAXPAGE(int pagecode)
{
double ye = (new Usersdata().cha().Count) / (pagecode *1.0);
int maxye = Convert.ToInt32(Math.Ceiling(ye));
return maxye;
}
3 组合查询和分页结合使用
先查询后分页（拼SQL语句）
数据访问类:同上面的组合查询
string sqls = "select top " + pagecode + " *from Users ";//带分页和查询条件的SQL语句
string sql2 = "select *from Users";//带查询条件的SQL的语句
string sqls1 = "";//查询条件sql语句
if (TextBox1.Text != "")
{
sqls += " where UserName like @a";
sqls1 += " where UserName like @a";
has.Add("@a", "%" + TextBox1.Text.Trim() + "%");
count++;
}
if (Drop_nation.SelectedValue != "0")
{
if (count != 0)
{
sqls += " and [email protected]";
sqls1 += " and [email protected]";
}
else
{
sqls += " WHERE [email protected]";
sqls1 += " WHERE [email protected]";
count++;
}
string sss = Drop_nation.SelectedValue.ToString();
has.Add("@b", sss);
count++;
}
if (count > 0)
{
sqls += " and UserName not in (select top " + ((Convert.ToInt32(Label1.Text) - 1) * pagecode) + " UserName from Users" + sqls1 + ")";
}
else
{
sqls += " where UserName not in (select top " + ((Convert.ToInt32(Label1.Text) - 1) * pagecode) + " UserName from Users)";
}//用label记录sql语句并隐藏，当上一页、下一页等可以从label中取出用
Label3.Text = sqls;
Label4.Text = sqls1;
Label5.Text = sql2 + sqls1;
//Repeater数据绑定
Repeater1.DataSource = new Usersdata().chas(Label3.Text, has);
Repeater1.DataBind();
时间： 2025-01-31 05:27:06