从 MS Access 检索数据并以另一种形式显示到标签

Posted 2023-05-07

【中文标题】从 MS Access 检索数据并以另一种形式显示到标签

【英文标题】：Retrieving data from MS Access and display it to label in another form

【发布时间】：2015-02-23 23:50:14

【问题描述】：

我在Form1 中的btnLogin 中有这段代码，用于从MS Access database 获取数据，我希望它显示在Form2using 标签中，但我不知道如何将其传递给Form2

private void btnLogin_Click(object sender, EventArgs e)
    
        connection.Open();
        OleDbCommand command = new OleDbCommand();
        command.Connection = connection;
        if ((this.txtUser.Text == "admin") && (this.txtPass.Text == "admin"))
        
            Form1 main = new Form1();
            main.txtHere.Text = txtUser.Text;
            main.Show();
            this.Hide();
        
        else 
            command.CommandText = "select * from StudentsTBL where LastName='" + txtUser.Text + "' and FirstName='" + txtPass.Text + "'";

            OleDbDataReader reader = command.ExecuteReader();
            int count = 0;
            while (reader.Read()) 
                count = count + 1;
                //count++;
            
            if (count == 1) 
                MessageBox.Show("Login Successful!");
                List<String> stdNo = new List<String>();
                List<String> middleName = new List<String>();
                List<String> section = new List<String>();
                List<String> year = new List<String>();
                List<String> sem = new List<String>();
                List<String> address = new List<String>();
                List<String> dob = new List<String>();
                List<String> gender = new List<String>();
                List<String> age = new List<String>();
                List<String> contact = new List<String>();
                List<String> desc = new List<String>();

                command = new OleDbCommand("select * from StudentsTBL", connection);
                reader = command.ExecuteReader();
                while (reader.Read())
                
                    stdNo.Add(reader["StudentNo"].ToString());
                    middleName.Add(reader["Middle"].ToString());
                    section.Add(reader["stdSection"].ToString());
                    year.Add(reader["stdYear"].ToString());
                    sem.Add(reader["stdSem"].ToString());
                    address.Add(reader["stdAddress"].ToString());
                    dob.Add(reader["stdDob"].ToString());
                    gender.Add(reader["stdGender"].ToString());
                    age.Add(reader["stdAge"].ToString());
                    contact.Add(reader["ContactNo"].ToString());
                    desc.Add(reader["stdDesc"].ToString());
                
                StudentProfile stdProfile = new StudentProfile(txtUser.Text, txtPass.Text);
                stdProfile.Show();
                this.Hide();
            
            else if (count > 1)
            
                MessageBox.Show("Duplicate username and password!!");
            
            else 
                MessageBox.Show("Login Failed!");
            
        
        connection.Close();
    

来源：Getting data from MS Access database and display it in a listbox

【问题讨论】：

嗯，什么Form2？你的 Label 字段的名称是什么？

我要将数据显示到form2

Forms are just classes

如果您试图让 Form1 与 Form2 对话，您可以使用委托或构造函数注入。参考***.com/a/27179975/1862333

【参考方案1】：

为什么你不使用结构？ 它会让你的喜欢很容易你可以一次处理很多信息 变量。

你为什么不做一个全局变量？ 它可以从您应用程序的任何部分获得。

我在GitHub 有这样的项目，你可以下载作为示例参考

    structure UserInfo
  public string stdNo;
  public string middleName;
  public string section;
  public string year;
  public string sem;
  public string address;
  public string dob;
  public string gender;
  public string age;
  public string contact;
  public string desc;


//===>Define a global variable to handle
public static UserInfo LoggedUsrInfo  = new UserInfo();

private void btnLogin_Click(object sender, EventArgs e)
    
        connection.Open();
        OleDbCommand command = new OleDbCommand();
        command.Connection = connection;
        if ((this.txtUser.Text == "admin") && (this.txtPass.Text == "admin"))
        
            Form1 main = new Form1();
            main.txtHere.Text = txtUser.Text;
            main.Show();
            this.Hide();
        
        else 
            command.CommandText = "select * from StudentsTBL where LastName='" + txtUser.Text + "' and FirstName='" + txtPass.Text + "'";
            DataTable Tbl = new DataTable();
            OleDbDataReader reader = command.ExecuteReader();
            Tbl.Load(reader,LoadOption.OverwriteChanges);//===>Retrieve data and load to datatble
            reader.Close();//Close the reader
            if (Tbl.Rows.Count > 0) //Count if the data table retrieve some info
                DataTable TblInfo = new DataTable();
                MessageBox.Show("Login Successful!");


                command = new OleDbCommand("select * from StudentsTBL", connection);
                reader = command.ExecuteReader();
                TblInfo.Load(reader,LoadOption.OverwriteChanges);
                reader.Close();//Close the reader
                    LoggedUsrInfo.stdNo = TblInfo.Rows[0]["StudentNo"].ToString();
                    LoggedUsrInfo.middleName = TblInfo.Rows[0]["Middle"].ToString();
                    LoggedUsrInfo.section = TblInfo.Rows[0]["stdSection"].ToString();
                    LoggedUsrInfo.year = TblInfo.Rows[0]["stdYear"].ToString();
                    LoggedUsrInfo.sem =TblInfo.Rows[0]["stdSem"].ToString();
                    LoggedUsrInfo.address = TblInfo.Rows[0]["stdAddress"].ToString();
                    LoggedUsrInfo.dob = TblInfo.Rows[0]["stdDob"].ToString();
                    LoggedUsrInfo.gender = TblInfo.Rows[0]["stdGender"].ToString();
                    LoggedUsrInfo.age = TblInfo.Rows[0]["stdAge"].ToString();
                    LoggedUsrInfo.contact = TblInfo.Rows[0]["ContactNo"].ToString();
                    LoggedUsrInfo.desc = TblInfo.Rows[0]["stdDesc"].ToString();

                StudentProfile stdProfile = new StudentProfile(txtUser.Text, txtPass.Text);
                stdProfile.Show();
                this.Hide();
            
            else if (count > 1)
            
                MessageBox.Show("Duplicate username and password!!");
            
            else 
                MessageBox.Show("Login Failed!");
            
        
        connection.Close();
    


/*
you can access to UserInfo calling in this way from your Form2
Load Event

Label1.Text = Form1.LoggedUsrInfo.middleName;

*/