c#项目实战_如何在C#中创建高级记录导航系统 datagridview写入数据
本教程是我们上一个主题“如何在C#中创建简单的记录导航”的续篇。但此时，我们将修改代码并添加更多附加控件，如第一条记录、最后一条记录和记录数。如下所示。
为了开始构建这个应用程序，让我们首先打开我们最后一个名为“student_info”的项目。然后添加按钮和标签。接下来，按照上图所示进行排列和设计。
这次我们将在四个按钮上添加功能，比如First、Previous、Next和Last。首先，双击“第一条记录”按钮。然后添加以下代码：
private void btnfirst_Click(object sender, EventArgs e){
//check if the current record is not equal to zero
if (curRecord != 0)
//set the current record to zero
curRecord = 0;
//call the Navaigate sub procedure
Navigate();
//set the record value
lblrecord.Text = curRecord + 1 + " of " + totRecord;
}
然后是“上一条记录”按钮。添加以下代码：
private void btnprev_Click(object sender, EventArgs e){
//check if the current record is greater than zero
if (curRecord > 0)
{
//then decrement the current record by one
curRecord = curRecord - 1;
//call the Navaigate sub procedure
Navigate();
//set the record value
lblrecord.Text = curRecord + 1 + " of " + totRecord;
}
}
“下一条记录”按钮。添加以下代码：
private void btnnext_Click(object sender, EventArgs e){
//check if the current record is not equal to the total Record minus by one
if (curRecord != totRecord - 1)
{
//increment the current record by one
curRecord = curRecord + 1;
//call the Navaigate sub procedure
Navigate();
//set the record value
lblrecord.Text = curRecord + 1 + " of " + totRecord;
}
}
最后是“最后记录”按钮。下面是代码：
private void btnlast_Click(object sender, EventArgs e){
//check if the current Record is not Equal to the total record
if (curRecord != totRecord)
//set the current record equal to total record
curRecord = totRecord - 1;
//call the Navaigate sub procedure
Navigate();
//set the record value
lblrecord.Text = curRecord + 1 + " of " + totRecord;
}
此时，您可以按“F5”或“开始”按钮来测试应用程序。
下面是这个应用程序使用的所有代码。
using System;using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.Data.OleDb;
namespace student_info
{
public partial class Form1 : Form
{
//declare new variable named dt as New Datatable
DataTable dt = new DataTable();
//this line of code used to connect to the server and locate the database (usermgt.mdb)
static string connection = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source= " + Application.StartupPath + "/studentdb.mdb";
OleDbConnection conn = new OleDbConnection(connection);
int curRecord = 0;
int totRecord = 0;
public Form1()
{
InitializeComponent();
}
private void btnload_Click(object sender, EventArgs e)
{
//create a new datatable
dt = new DataTable();
//create our SQL SELECT statement
string sql = "Select * from tblstudent";
//then we execute the SQL statement against the Connection using OleDBDataAdapter
OleDbDataAdapter da = new OleDbDataAdapter(sql, conn);
//we fill the result to dt which declared above as datatable
da.Fill(dt);
//set the curRecord to zero
curRecord = 0;
//get the total number of record available in the database and stored to totRecord Variable
totRecord = dt.Rows.Count;
//then we populate the datagridview by specifying the datasource equal to dt
dataGridView1.DataSource = dt;
}
private void dataGridView1_CellClick(object sender, DataGridViewCellEventArgs e)
{
//it checks if the row index of the cell is greater than or equal to zero
if (e.RowIndex >= 0)
{
//gets a collection that contains all the rows
DataGridViewRow row = this.dataGridView1.Rows[e.RowIndex];
//populate the textbox from specific value of the coordinates of column and row.
txtid.Text = row.Cells[0].Value.ToString();
txtfname.Text = row.Cells[1].Value.ToString();
txtlname.Text = row.Cells[2].Value.ToString();
comboBox1.Text = row.Cells[3].Value.ToString();
txtgender.Text = row.Cells[4].Value.ToString();
txtaddress.Text = row.Cells[5].Value.ToString();
}
}
private void Form1_Load(object sender, EventArgs e)
{
loadDatatoCombobox();
}
private void loadDatatoCombobox()
{
//create a new datatable
DataTable table = new DataTable();
//create our SQL SELECT statement
string sql = "Select course from tblstudent";
try
{
conn.Open();
//then we execute the SQL statement against the Connection using OleDBDataAdapter
OleDbDataAdapter da = new OleDbDataAdapter(sql, conn);
//we fill the result to dt which declared above as datatable
da.Fill(table);
//we add new entry to our datatable manually
//becuase Select Course is not Available in the Database
table.Rows.Add("Select Course");
//set the combobox datasource
comboBox1.DataSource = table;
//choose the specific field to display
comboBox1.DisplayMember = "course";
comboBox1.ValueMember = "course";
//set default selected value
comboBox1.SelectedValue = "Select Course";
}
catch (Exception ex)
{
//this will display some error message if something
//went wrong to our code above during execution
MessageBox.Show(ex.ToString());
}
}
private void Navigate()
{
txtid.Text = dt.Rows[curRecord][0].ToString();
txtfname.Text = dt.Rows[curRecord][1].ToString();
txtlname.Text = dt.Rows[curRecord][2].ToString();
comboBox1.Text = dt.Rows[curRecord][3].ToString();
txtgender.Text = dt.Rows[curRecord][4].ToString();
txtaddress.Text = dt.Rows[curRecord][5].ToString();
}
private void btnprev_Click(object sender, EventArgs e)
{
//check if the current record is greater than zero
if (curRecord > 0)
{
//then decrement the current record by one
curRecord = curRecord - 1;
//call the Navaigate sub procedure
Navigate();
//set the record value
lblrecord.Text = curRecord + 1 + " of " + totRecord;
}
}
private void btnnext_Click(object sender, EventArgs e)
{
//check if the current record is not equal to the total Record minus by one
if (curRecord != totRecord - 1)
{
//increment the current record by one
curRecord = curRecord + 1;
//call the Navaigate sub procedure
Navigate();
//set the record value
lblrecord.Text = curRecord + 1 + " of " + totRecord;
}
}
private void btnfirst_Click(object sender, EventArgs e)
{
//check if the current record is not equal to zero
if (curRecord != 0)
//set the current record to zero
curRecord = 0;
//call the Navaigate sub procedure
Navigate();
//set the record value
lblrecord.Text = curRecord + 1 + " of " + totRecord;
}
private void btnlast_Click(object sender, EventArgs e)
{
//check if the current Record is not Equal to the total record
if (curRecord != totRecord)
//set the current record equal to total record
curRecord = totRecord - 1;
//call the Navaigate sub procedure
Navigate();
//set the record value
lblrecord.Text = curRecord + 1 + " of " + totRecord;
}
}
}
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