1、功能需求

本实例将通过c# winform实现简单的分页功能，需要的基础知识有SQL语句，c#语言基础以及c# winform的一些简单知识。

2、界面设计

这是一个简单的分页查询的界面，可以输入任意字段进行查询，这四个字段在数据准备会提到，整体界面如图1所示。

图1

中间显示是一个DataGridView，编辑好列和id，SortMode选择Automatic，意思是所有列自动铺满DataGridView，如图2所示。

图2

3、数据准备

本实例涉及到删查改，因此要有数据表以及对数据表进行操作的代码。数据库表非常简单，如图3所示，分别有对应四个字段。

图3

later_back模型类对应数据库操作类代码如下：

using MySql.Data.MySqlClient;

using System;

using System.Collections.Generic;

using System.Data;

using System.Linq;

using System.Text;

using System.Threading.Tasks;

using System.Windows.Forms;

using WindowsFormsApp1.Bean;

namespace WindowsFormsApp1.SqlHelper

{

class LaterBackHelper

{

public LaterBackHelper(){}

public void insert(LaterBack laterBack)

{

string sql = "insert into later_back(dormitory_id,student_no,time,reason) values('" + laterBack.Dormitory_id + "','" + laterBack.Student_no + "'," + "'" + laterBack.Time + "',"

+ "'" + laterBack.Reason + "')";

try

{

int iRet = SqlHelperBase.ExecuteSql(sql);

if (iRet > 0)

{

MessageBox.Show("新增成功", "系统提示");

}

else

{

MessageBox.Show("新增失败", "系统提示");

}

}

catch (Exception)

{

throw;

}

}

public int update(LaterBack laterBack)

{

string sql = "update later_back set reason='" + laterBack.Reason + "' where student_no= '" + laterBack.Student_no + "' and"

+ " time = '" + laterBack.Time + "' and " + " dormitory_id= '" + laterBack.Dormitory_id + "'";

try

{

int iRet = SqlHelperBase.ExecuteSql(sql);//这里返回的是受影响的行数，为int值。可以根据返回的值进行判断是否插入成功。

if (iRet > 0)

{

MessageBox.Show("修改成功", "系统提示");

}

else

{

MessageBox.Show("修改失败", "系统提示");

}

return iRet;

}

catch (Exception)

{

throw;

}

}

public int delete(LaterBack laterBack)

{

string sql = "delete from later_back where dormitory_id='" + laterBack.Dormitory_id + "' and" + " student_no= '" + laterBack.Student_no + "' and"

+ " time = '" + laterBack.Time + "' and" + " reason= '" + laterBack.Reason+"'";

try

{

int iRet = SqlHelperBase.ExecuteSql(sql);//这里返回的是受影响的行数，为int值。可以根据返回的值进行判断是否插入成功。

if (iRet > 0)

{

MessageBox.Show("删除成功", "系统提示");

}

else

{

MessageBox.Show("删除失败", "系统提示");

}

return iRet;

}

catch (Exception)

{

throw;

}

}

public List<LaterBack> getAllLaterBacks()

{

List<LaterBack> laterBacks= new List<LaterBack>();

string sql = "select * from later_back";

MySqlDataReader mySqlDataReader = SqlHelperBase.ExecuteReader(sql);

while (mySqlDataReader.Read())

{

LaterBack laterBack = new LaterBack(int.Parse(mySqlDataReader[0].ToString()), int.Parse(mySqlDataReader[1].ToString()), mySqlDataReader[2].ToString(),

mySqlDataReader[3].ToString());

laterBacks.Add(laterBack);

}

mySqlDataReader.Close();

return laterBacks;

}

public List<LaterBack> getAllLaterBacks(int student_no)

{

List<LaterBack> laterBacks= new List<LaterBack>();

string sql = "select * from later_back where student_no ='" + student_no + "'";

MySqlDataReader mySqlDataReader = SqlHelperBase.ExecuteReader(sql);

while (mySqlDataReader.Read())

{

LaterBack laterBack = new LaterBack(int.Parse(mySqlDataReader[0].ToString()), int.Parse(mySqlDataReader[1].ToString()), mySqlDataReader[2].ToString(),

mySqlDataReader[3].ToString());

laterBacks.Add(laterBack);

}

mySqlDataReader.Close();

return laterBacks;

}

public DataSet getAllDataSet()

{

string sql = "select * from later_back";

return SqlHelperBase.GetDataSet(sql);

}

//模糊查询

public DataSet getDataSet(LaterBack laterBack)

{

string sql="";

if(laterBack.Student_no != -1)

{

if (laterBack.Dormitory_id != -1) sql = "select * from later_back where dormitory_id like '%" + laterBack.Dormitory_id

+ "%' and student_no like '%" + laterBack.Student_no + "%' and time like '%" + laterBack.Time

+ "%' and reason like '%" + laterBack.Reason + "%'";

else sql = "select * from later_back where student_no like '%" + laterBack.Student_no + "%' and time like '%" + laterBack.Time

+ "%' and reason like '%" + laterBack.Reason + "%'";

}

else

{

if (laterBack.Dormitory_id != -1) sql = "select * from later_back where dormitory_id like '%" + laterBack.Dormitory_id

+ "%' and time like '%" + laterBack.Time+ "%' and reason like '%" + laterBack.Reason + "%'";

else sql = "select * from later_back where time like '%" + laterBack.Time

+ "%' and reason like '%" + laterBack.Reason + "%'";

}

return SqlHelperBase.GetDataSet(sql);

}

}

}

4、源码实现

实现分页时，我的思想是，在每次查询时得到一个dataset1，然后在分页时根据一个from_index和一个end_index去得到当前页面要显示的dataset2，用dataset2来刷新当前要显示的数据，然后在dataset2里头支持行数据的修改与删除，可能从这么写不大合适，但是能完成分页的功能，仅供参考。源码如下：

using MySql.Data.MySqlClient;

using System;

using System.Collections.Generic;

using System.ComponentModel;

using System.Data;

using System.Drawing;

using System.Linq;

using System.Text;

using System.Threading.Tasks;

using System.Windows.Forms;

using WindowsFormsApp1.Bean;

using WindowsFormsApp1.CacheUtil;

using WindowsFormsApp1.SqlHelper;

namespace WindowsFormsApp1

{

public partial class StudentLateBackPanelRightSelect : Form

{

private LaterBackHelper laterBackHelper;

private string []page_counts = { "5","6","7","8","9","10","15","20"};

private int total_page, page_step, current_page_index, total_count;

private DataSet dataSet;

public StudentLateBackPanelRightSelect()

{

laterBackHelper = new LaterBackHelper();

dataSet = laterBackHelper.getAllDataSet();

total_count = dataSet.Tables[0].Rows.Count;

page_step = 5;

total_page = Convert.ToInt16(Math.Ceiling(Convert.ToDouble(total_count) / page_step));

InitializeComponent();

initView(GetViewDataSet(dataSet,1,5));

comboBox_page_count.Items.AddRange(page_counts);

comboBox_page_count.SelectedIndex = 0;

label_all_item_count.Text = total_count.ToString();

label_page_count.Text = total_page.ToString();

}

//每次点击时刷新全局数据

private void initDataPage(int total_count,int page_step, int current_page_index)

{

this.total_count = total_count;

this.page_step = page_step;

this.total_page = Convert.ToInt16(Math.Ceiling(Convert.ToDouble(total_count) / page_step));

this.current_page_index = current_page_index;

}

//初始化界面并加载数据

private void initView(DataSet ds)

{

dataGridView.AutoGenerateColumns = false;

dataGridView.DataSource = ds.Tables[0];

this.dataGridView.Columns["dor_id"].DataPropertyName = ds.Tables[0].Columns[0].ToString();

this.dataGridView.Columns["stu_id"].DataPropertyName = ds.Tables[0].Columns[1].ToString();

this.dataGridView.Columns["time"].DataPropertyName = ds.Tables[0].Columns[2].ToString();

this.dataGridView.Columns["reason"].DataPropertyName = ds.Tables[0].Columns[3].ToString();

}

private void button_select_Click(object sender, EventArgs e)

{

string stu_id = textBox_stu_id.Text, dor_id = textBox_dor_id.Text, time = textBox_time.Text, reason = textBox_reason.Text;

if(stu_id.Equals("")&& dor_id.Equals("") && time.Equals("") && reason.Equals(""))

{

return;

}

if (dor_id.Equals("")) dor_id = "-1";

if (stu_id.Equals("")) stu_id = "-1";

LaterBack laterBack = new LaterBack(int.Parse(dor_id), int.Parse(stu_id), time, reason);

dataSet.Clear();

dataSet = laterBackHelper.getDataSet(laterBack);

initDataPage(dataSet.Tables[0].Rows.Count, page_step, 1);

initView(GetViewDataSet(dataSet, 1, page_step));

label_page_count.Text = total_page.ToString();

label_page_range.Text = "1-" + page_step.ToString();

label_all_item_count.Text = total_count.ToString();

}

//只能输入数字

private void only_num_press(object sender, KeyPressEventArgs e)

{

if (!(Char.IsNumber(e.KeyChar)) && e.KeyChar != (char)8)

{

e.Handled = true;

}

}

//对行数据进行删除或修改操作

private void dataGridView_CellClick(object sender, DataGridViewCellEventArgs e)

{

string action = dataGridView.Columns[e.ColumnIndex].Name;//操作类型

var cells = dataGridView.Rows[e.RowIndex].Cells;

LaterBack laterBack = new LaterBack(int.Parse(cells[0].Value.ToString()), int.Parse(cells[1].Value.ToString()), cells[2].Value.ToString(), cells[3].Value.ToString());

switch (action)

{

case "update":

//获取相应列的数据ID,弹出加载了该ID数据详细信息的Form,用以修改

StudentLateBackPanelRightUpdate studentLateBackPanelRightUpdate = new StudentLateBackPanelRightUpdate(laterBack);

studentLateBackPanelRightUpdate.Show();

break;

case "delete":

if (MessageBox.Show("确定删除这行数据吗?", "删除提示", MessageBoxButtons.OKCancel) == DialogResult.OK)

{

//获取相应列的数据ID,删除此数据记录

int result = laterBackHelper.delete(laterBack);

if(result > 0)

{

//dataSet.Clear();

dataSet = laterBackHelper.getAllDataSet();

initDataPage(dataSet.Tables[0].Rows.Count,page_step,1);

initView(GetViewDataSet(dataSet,1,page_step));

label_page_count.Text = total_page.ToString();

label_page_range.Text = "1-" + page_step.ToString();

label_all_item_count.Text = total_count.ToString();

}

}

break;

default:

break;

}

}

//获取要显示的数据源

public DataSet GetViewDataSet(DataSet a_ds,int from_index,int end_index)

{

//首先先声明一个DataSet对象和一个DataTable对象

DataSet l_ds = new DataSet();

DataTable l_dt = new DataTable();

//构建DataTable对象的列值

l_dt.Columns.Add("dor_id");//这些列名就是返回的DataSet的列名，可以随意添加

l_dt.Columns.Add("stu_id");

l_dt.Columns.Add("time");

l_dt.Columns.Add("reason");

//遍历传进来的DataSet的值，并对DataTable进行赋值操作

for (int i = from_index - 1; i < end_index ; i++)

{

DataRow dr = l_dt.NewRow();//首先新增一行，然后对其进行赋值

dr["dor_id"] = a_ds.Tables[0].Rows[i][0].ToString().Trim();

dr["stu_id"] = a_ds.Tables[0].Rows[i][1].ToString().Trim();

dr["time"] = a_ds.Tables[0].Rows[i][2].ToString().Trim();

dr["reason"] = a_ds.Tables[0].Rows[i][3].ToString().Trim();

l_dt.Rows.Add(dr);//这里一定要add进去

}

l_ds.Tables.Add(l_dt);//这里也不能忘记

return l_ds;

}

//combobox更改触发事件

private void combobox_selected_listen(object sender, EventArgs e)

{

page_step = int.Parse(comboBox_page_count.SelectedItem.ToString());

textBox_page_count.Text = 1.ToString();

label_page_range.Text = "1-" + page_step.ToString();

total_page = Convert.ToInt16( Math.Ceiling(Convert.ToDouble(total_count) / page_step));

label_page_count.Text = total_page.ToString();

initView(GetViewDataSet(dataSet, 1, page_step));

}

//输入页数变化

private void page_count_change(object sender, EventArgs e)

{

if (textBox_page_count.Text.Equals("")) return;

if (int.Parse(textBox_page_count.Text) < 1)

{

MessageBox.Show("输入页数不能小于1", "系统提示");

return;

}

if (int.Parse(textBox_page_count.Text) > total_page)

{

MessageBox.Show("输入页数超过总页数", "系统提示");

return;

}

current_page_index = int.Parse(textBox_page_count.Text);

var view_range = (current_page_index - 1)* page_step ;

if (view_range + page_step < total_count) {

initView(GetViewDataSet(dataSet, view_range + 1, view_range + page_step));

label_page_range.Text = (view_range + 1).ToString() + "-" + (view_range + page_step).ToString();

}

else {

initView(GetViewDataSet(dataSet, view_range + 1, total_count));

label_page_range.Text = (view_range + 1).ToString() + "-" + total_count.ToString();

}

}

private void button_first_page_Click(object sender, EventArgs e)

{

current_page_index = 1;

var view_range = (current_page_index - 1) * page_step;

initView(GetViewDataSet(dataSet, view_range + 1, view_range + page_step));

label_page_range.Text = (view_range + 1).ToString() + "-" + page_step.ToString();

textBox_page_count.Text = current_page_index.ToString();

}

private void button_previous_page_Click(object sender, EventArgs e)

{

if (current_page_index == 1) return;

current_page_index -= 1;

var view_range = (current_page_index - 1) * page_step;

initView(GetViewDataSet(dataSet, view_range + 1, view_range + page_step));

label_page_range.Text = (view_range + 1).ToString() + "-" + (view_range + page_step).ToString();

textBox_page_count.Text = current_page_index.ToString();

}

private void button_next_page_Click(object sender, EventArgs e)

{

if (current_page_index == total_page) return;

current_page_index += 1;

var view_range = (current_page_index - 1) * page_step;

if (view_range + page_step < total_count)

{

initView(GetViewDataSet(dataSet, view_range + 1, view_range + page_step));

label_page_range.Text = (view_range + 1).ToString() + "-" + (view_range + page_step).ToString();

}

else

{

initView(GetViewDataSet(dataSet, view_range + 1, total_count));

label_page_range.Text = (view_range + 1).ToString() + "-" + total_count.ToString();

}

textBox_page_count.Text = current_page_index.ToString();

}

private void button_last_page_Click(object sender, EventArgs e)

{

current_page_index = total_page;

var view_range = (current_page_index - 1) * page_step;

initView(GetViewDataSet(dataSet, view_range + 1, total_count));

label_page_range.Text = (view_range + 1).ToString() + "-" + total_count.ToString();

textBox_page_count.Text = current_page_index.ToString();

}

}

}

5、结果

程序运行结果如图4和图5所示，更改每页条数，或者输入页数时都能跳转到相应页面，所有功能都正常，至此，简单的分页功能就实现，如果有任何问题，欢迎给我留言。

图4

图5