Webform（分页、组合查询）

一、分页

1.写查询方法：

public List<Student> Select(int PageCount, int PageNumber)
    {//PageCount为每页显示条数，PageNumber为当前第几页
        List<Student> list = new List<Student>();
        cmd.CommandText = "select top " + PageCount + "  *from Student where Code not in (select top "+(PageCount * (PageNumber - ))+" Code from Student)";
        conn.Open();
        SqlDataReader dr = cmd.ExecuteReader();
        if (dr.HasRows)
        {
            while (dr.Read())
            {
                Student s = new Student();
                s.Code = dr[].ToString();
                s.Name = dr[].ToString();
                s.Sex = Convert.ToBoolean(dr[]);
                s.Birthday = Convert.ToDateTime(dr[]);
                s.SubjectCode = dr[].ToString();
                s.Nation = dr[].ToString();
                list.Add(s);
            }
        }
        conn.Close();
        return list;
    }

查询方法

2.C#代码

int PageCount = ; //每页显示条数
    protected void Page_Load(object sender, EventArgs e)
    {
        if(!IsPostBack)
        {
        List<Student> list = new StudentData().Select(PageCount,);
        Repeater1.DataSource = list;
        Repeater1.DataBind();
        Label2.Text = "";//第一页
        Label3.Text = MaxPageNumber().ToString();//总页数
}
  for (int i = ; i <= MaxPageNumber(); i++)
    {
        DropDownList2.Items.Add(new ListItem(i.ToString(), i.ToString()));
    }
}

Page_Load

public int MaxPageNumber()
    {
        List<Student> list = new StudentData().select();

        double de = list.Count / (PageCount * 1.0);

        int aa = Convert.ToInt32(Math.Ceiling(de));//取上限
        return aa;
    }

计算总页数

void DropDownList2_SelectedIndexChanged(object sender, EventArgs e)
    {
        Repeater1.DataSource = new StudentData().Select(PageCount, Convert.ToInt32(DropDownList2.SelectedValue));
        Repeater1.DataBind();
        Label2.Text = DropDownList2.SelectedValue;
    }

快速跳转

void btn_end_Click(object sender, EventArgs e)
    {
        List<Student> list = new StudentData().Select(PageCount, MaxPageNumber());
        Repeater1.DataSource = list;
        Repeater1.DataBind();
        Label2.Text = MaxPageNumber().ToString();
    }

跳转到最后一页

void btn_first_Click(object sender, EventArgs e)
    {
        List<Student> list = new StudentData().Select(PageCount, );
        Repeater1.DataSource = list;
        Repeater1.DataBind();
        Label2.Text ="";
    }

跳转到第一页

void btn_prev_Click(object sender, EventArgs e)
    {
        int pagec = Convert.ToInt32(Label2.Text) - ;
        if (pagec <=)//判断是不是第一页，是的话什么也不干
        {
            return;
        }
        List<Student> list = new StudentData().Select(PageCount, pagec);
        Repeater1.DataSource = list;
        Repeater1.DataBind();
        Label2.Text = pagec.ToString();
    }

跳转到上一页

void btn_next_Click(object sender, EventArgs e)
    {
         int pagec = Convert.ToInt32(Label2.Text) + ;
         if (pagec > MaxPageNumber())// 判断是不是最后一页，是的话什么也不干
         {
             return;
         }
        Repeater1.DataSource = new StudentData().Select(PageCount,pagec);
        Repeater1.DataBind();
        Label2.Text = pagec.ToString();

    }

跳转到下一页

二、组合查询

1.查询方法

 public List<Student> Select(string tsql,Hashtable hh)
     {
         List<Student> list = new List<Student>();
         cmd.CommandText = tsql;
         cmd.Parameters.Clear();
         foreach( string s in hh.Keys)
         {
         cmd.Parameters.Add(s,hh[s]);
         }
         conn.Open();
         SqlDataReader dr = cmd.ExecuteReader();
         if (dr.HasRows)
         {
             while (dr.Read())
             {
                 Student s = new Student();
                 s.Code = dr[].ToString();
                 s.Name = dr[].ToString();
                 s.Sex = Convert.ToBoolean(dr[]);
                 s.Birthday = Convert.ToDateTime(dr[]);
                 s.SubjectCode = dr[].ToString();
                 s.Nation = dr[].ToString();
                 list.Add(s);
             }
         }
         conn.Close();
         return list;
     }

查询方法

public List<Subject> Select(string name)
    {
        List<Subject> list = new List<Subject>();
        cmd.CommandText = "select *from Subject where SubjectName like @a ";
        cmd.Parameters.Clear();
        cmd.Parameters.Add("@a","%"+name+"%");
        conn.Open();
        SqlDataReader dr = cmd.ExecuteReader();
        if (dr.HasRows)
        {
            while (dr.Read())
            {
                Subject s = new Subject();
                s.SubjectCode = dr[].ToString();
                s.SubjectName = dr[].ToString();
                list.Add(s);
            }
        }
        conn.Close();

        return list;
    }

2.c#代码

 void Button2_Click(object sender, EventArgs e)
     {
         int count = ;//判断tsql是否含有where
         Hashtable hs = new Hashtable();//哈希表
         string tsql = "select * from Student";
         //性别
         if(!string.IsNullOrEmpty(tb_sex.Text.Trim()))//输入的性别非空
         {
             if (tb_sex.Text.Trim() == "男")
             {
                 tsql += " where Sex = @a";
                 hs.Add("@a", "true");
                 count++;
             }
             else if (tb_sex.Text.Trim() == "女")
             {
                 tsql += " where Sex = @a";
                 hs.Add("@a", "false");
                 count++;
             }
         }
         //年龄
         if (!string.IsNullOrEmpty(tb_age.Text.Trim()))//判断年龄输入框是否为空
         {
             int a = DateTime.Now.Year;
             try {//异常保护，输入框只能是数字
              int ag=  Convert.ToInt32(tb_age.Text.Trim());
              int g = a - ag;
              DateTime d = Convert.ToDateTime(g.ToString()+"-1-1");
              if (DropDownList3.SelectedValue == ">=")//列表框显示值为<=,小于某个年龄
              {
                  if (count == )
                  {
                      tsql += " where Birthday " + DropDownList3.SelectedValue + "@b";
                  }
                  else
                  {
                      tsql += " and Birthday " + DropDownList3.SelectedValue + "@b";
                  }
                  hs.Add("@b", d);
              }
              else//大于某个年龄
              {
                  DateTime dd = Convert.ToDateTime(g.ToString() + "-12-31");
                  if (count == )
                  {
                      tsql += " where Birthday " + DropDownList3.SelectedValue + "@b";
                  }
                  else
                  {
                      tsql += " and Birthday " + DropDownList3.SelectedValue + "@b";
                  }
                  hs.Add("@b", dd);
              }
              count++;
             }
             catch {
             }
         }
         if (!string.IsNullOrEmpty(tb_s.Text.Trim()))//专业非空
         {
             List<Subject> li = new SubjectData().Select(tb_s.Text.Trim());
             if (li.Count <= )
             {
             }
             else
             { string u ="";
             int cou = ;
                 foreach(Subject ub in li)
                 {
                     u = ub.SubjectCode;
                     if (cou == )//第一条数据
                     {
                         if (count == )
                         {
                             tsql += " where SubjectCode =@c";
                         }
                         else
                         {
                             tsql += " and SubjectCode =@c";
                         }
                         hs.Add("@c", u);
                         cou++;
                     }
                     else
                     {
                         tsql += " or SubjectCode =@d";
                         hs.Add("@d", u);
                     }
                 }
             }
         }
         Repeater1.DataSource = new StudentData().Select(tsql, hs);
         Repeater1.DataBind();
     }

查询按钮赋功能