C# Inserting Data from a form into an access Database

问题

I started learning about C# and have become stuck with inserting information from textboxes into an Access database when a click button is used.

The problem I get is during the adding process. The code executes the Try... Catch part and then returns an error saying "Microsoft Access Database Engine" and doesn't give any clues.

Here is the code:

namespace WindowsFormsApplication1
{
    public partial class FormNewUser : Form
    {
        public FormNewUser()
        {
            InitializeComponent();
        }

        private void BTNSave_Click(object sender, EventArgs e)
        {
            OleDbConnection conn = new OleDbConnection();
            conn.ConnectionString = @"Provider=Microsoft.ACE.OLEDB.12.0;Data Source=C:\Users\kenny\Documents\Visual Studio 2010\Projects\Copy Cegees\Cegees\Cegees\Login.accdb";

            String Username = TEXTNewUser.Text;
            String Password = TEXTNewPass.Text;

            OleDbCommand cmd = new OleDbCommand("INSERT into Login (Username, Password) Values(@Username, @Password)");
            cmd.Connection = conn;

            conn.Open();

            if (conn.State == ConnectionState.Open)
            {
                cmd.Parameters.Add("@Username", OleDbType.VarChar).Value = Username;
                cmd.Parameters.Add("@Password", OleDbType.VarChar).Value = Password;

                try
                {
                    cmd.ExecuteNonQuery();
                    MessageBox.Show("Data Added");
                    conn.Close();
                }
                catch (OleDbException ex)
                {
                    MessageBox.Show(ex.Source);
                    conn.Close();
                }
            }
            else
            {
                MessageBox.Show("Connection Failed");
            }
        }
    }
}

回答1:

Password is a reserved word. Bracket that field name to avoid confusing the db engine.

INSERT into Login (Username, [Password])

回答2:

This answer will help in case, If you are working with Data Bases then mostly take the help of try-catch block statement, which will help and guide you with your code. Here i am showing you that how to insert some values in Data Base with a Button Click Event.

 private void button2_Click(object sender, EventArgs e)
    {
        System.Data.OleDb.OleDbConnection conn = new System.Data.OleDb.OleDbConnection();
        conn.ConnectionString = @"Provider=Microsoft.ACE.OLEDB.12.0;" +
    @"Data source= C:\Users\pir fahim shah\Documents\TravelAgency.accdb";

     try
       {
           conn.Open();
           String ticketno=textBox1.Text.ToString();                 
           String Purchaseprice=textBox2.Text.ToString();
           String sellprice=textBox3.Text.ToString();
           String my_querry = "INSERT INTO Table1(TicketNo,Sellprice,Purchaseprice)VALUES('"+ticketno+"','"+sellprice+"','"+Purchaseprice+"')";

            OleDbCommand cmd = new OleDbCommand(my_querry, conn);
            cmd.ExecuteNonQuery();

            MessageBox.Show("Data saved successfuly...!");
          }
         catch (Exception ex)
         {
             MessageBox.Show("Failed due to"+ex.Message);
         }
         finally
         {
             conn.Close();
         }

回答3:

and doesnt give any clues

Yes it does, unfortunately your code is ignoring all of those clues. Take a look at your exception handler:

catch (OleDbException  ex)
{
    MessageBox.Show(ex.Source);
    conn.Close();
}

All you're examining is the source of the exception. Which, in this case, is "Microsoft Access Database Engine". You're not examining the error message itself, or the stack trace, or any inner exception, or anything useful about the exception.

Don't ignore the exception, it contains information about what went wrong and why.

There are various logging tools out there (NLog, log4net, etc.) which can help you log useful information about an exception. Failing that, you should at least capture the exception message, stack trace, and any inner exception(s). Currently you're ignoring the error, which is why you're not able to solve the error.

In your debugger, place a breakpoint inside the catch block and examine the details of the exception. You'll find it contains a lot of information.

回答4:

 private void Add_Click(object sender, EventArgs e) {
 OleDbConnection con = new OleDbConnection(@ "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=C:\Users\HP\Desktop\DS Project.mdb");
 OleDbCommand cmd = con.CreateCommand();
 con.Open();
 cmd.CommandText = "Insert into DSPro (Playlist) values('" + textBox1.Text + "')";
 cmd.ExecuteNonQuery();
 MessageBox.Show("Record Submitted", "Congrats");
 con.Close();
} 

回答5:

  private void addToolStripMenuItem_Click(object sender, EventArgs e)
    {
        Form2 klass = new Form2();
        klass.ShowDialog();
        string my_querry = "INSERT INTO test(Sname,Ssurname,SNumber,SDNP,Sexam)VALUES('" + klass.getName() + "','" + klass.getSurname() + "','" + klass.getNumber() + "','" + klass.getDNP() + "','" + klass.getExam() + "')";
        dbconn = new OleDbConnection(conn + dbfile);
        dbconn.Open();
        try
        {
            OleDbCommand cmd = new OleDbCommand(my_querry, dbconn);
            cmd.ExecuteNonQuery();
            MessageBox.Show("success....");
        }
        catch(Exception ex)
        {
            MessageBox.Show(ex.Message);
        }
        dbconn.Close();
    }

来源：https://stackoverflow.com/questions/19275557/c-sharp-inserting-data-from-a-form-into-an-access-database