C# winform分页查询的实现示例

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

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