在 C# 中将记录插入 Microsoft Access 数据库

Question

我正在插入数据以使用 C# 访问 2000-2003 文件格式数据库。当我有一个包含 2 个字段的数据库时，查询工作正常，但当有更多字段时，它就不起作用了。

我有两个相同的代码，我无法找到问题。

using System.Data.OleDb;    // By using this namespace I can connect to the Access Database.

namespace WindowsFormsApplication1
{
    public partial class Form1 : Form
    {
        private OleDbConnection myconn;
        public Form1()
        {
            InitializeComponent();
            myconn = new OleDbConnection(@"Provider=Microsoft.Jet.OLEDB.4.0;Data Source=C:\Users\leelakrishnan\Desktop\NewManageContacts.mdb");
        }

        private void Form1_Load(object sender, EventArgs e)
        {
            // TODO: This line of code loads data into the 'newManageContactsDataSet.Contacts' table. You can move, or remove it, as needed.
           // this.contactsTableAdapter.Fill(this.newManageContactsDataSet.Contacts);
            // TODO: This line of code loads data into the 'newManageContactsDataSet.Contacts' table. You can move, or remove it, as needed.
            this.contactsTableAdapter.Fill(this.newManageContactsDataSet.Contacts);

        }


        private void button1_Click(object sender, EventArgs e)
        {
            OleDbCommand cmd = new OleDbCommand();
            cmd.CommandType = CommandType.Text;
           // string query = "insert into Contacts (fname,lname,llnum,mobnum,e-mail,street,city,country) values ('" + textBox1.Text + "','" + textBox2.Text + "','" + textBox3.Text + "','" + textBox4.Text + "','" + textBox5.Text + "','" + textBox6.Text + "','" + textBox7.Text + "','" + textBox8.Text + "')";
            cmd.CommandText = @"insert into Contacts (fname,lname,llnum,mobnum,e-mail,street,city,country) values ('" + textBox1.Text + "','" + textBox2.Text +  "','" + textBox3.Text + "','" + textBox4.Text + "','" + textBox5.Text + "','" + textBox6.Text + "','" + textBox7.Text + "','" + textBox8.Text + "')";
            cmd.Connection = myconn;
            myconn.Open();
            cmd.ExecuteNonQuery();
            System.Windows.Forms.MessageBox.Show("User Account Succefully Created", "Caption", MessageBoxButtons.OKCancel, MessageBoxIcon.Information);
            myconn.Close();
        }

        private void button2_Click(object sender, EventArgs e)
        {
            textBox1.Text = "";
            textBox2.Text = "";
            textBox3.Text = "";
            textBox4.Text = "";
            textBox5.Text = "";
            textBox6.Text = "";
            textBox7.Text = "";
            textBox8.Text = "";

        }

        private void textBox1_TextChanged(object sender, EventArgs e)
        {

        }

    }
}

这是只有 2 个字段的表格的代码

public partial class Form1 : Form
{
    private OleDbConnection myCon;
    public Form1()
    {
        InitializeComponent();
        myCon = new OleDbConnection(@"Provider=Microsoft.Jet.OLEDB.4.0;Data Source=C:\Users\leelakrishnan\Desktop\Database1.mdb");
    }

    private void Form1_Load(object sender, EventArgs e)
    {
        // TODO: This line of code loads data into the 'database1DataSet.Table1' table. You can move, or remove it, as needed.
        this.table1TableAdapter.Fill(this.database1DataSet.Table1);

    }

    private void button1_Click(object sender, EventArgs e)
    {
        OleDbCommand cmd = new OleDbCommand();
        cmd.CommandType = CommandType.Text;
        cmd.CommandText = "insert into Table1 (name,fname) values ('" + textBox1.Text + "','" + textBox2.Text + "')";
        cmd.Connection = myCon;
        myCon.Open();
        cmd.ExecuteNonQuery();
        System.Windows.Forms.MessageBox.Show("User Account Succefully Created", "Caption", MessageBoxButtons.OKCancel, MessageBoxIcon.Information);
        myCon.Close();

    }

    private void button2_Click(object sender, EventArgs e)
    {
        textBox1.Text = "";
        textBox2.Text = "";
    }
}

Answer 1

您尝试插入的额外字段可能具有不易连接到有效 SQL 语句中的值。例如：

string field1 = "meh";
string field2 = "whatever";
string field3 = "'Ahoy!' bellowed the sailor.";
var cmd = new SqlCommand(
    "INSERT INTO blah (x, y, z) VALUES ('" + field1 + "', '" + field2 + "', '" + field3 + '")");

根据上述输入，想象一下连接的 SQL 会是什么样子。

更糟糕的是，想象一下如果有人在您的表单中输入此 SQL，您将要执行的 SQL：

field3 = "Bobby'); DROP TABLE Users; -- ";

通过cmd.Parameters.Add 或AddRange 使用参数化查询（描述为here）。上面的例子可以这样修改：

var cmd = new SqlCommand("INSERT INTO blah (x, y, z) VALUES (@x, @y, @z)");
cmd.Parameters.AddRange(new[] {
    new SqlParameter("@x", field1),
    new SqlParameter("@y", field2),
    new SqlParameter("@z", field2)
    });

Answer 2

此代码公开：

OleDbConnection con = new OleDbConnection(@"Provider = Microsoft.Jet.OLEDB.4.0; Data Source = C:\Users\Mohammadhoseyn_mehri\Documents\Data.mdb");

这个singup按钮的代码：

 try
 {
     createaccount();
     else
     {
         MessageBox.Show("Please re-enter your password");
     }
 }
 catch(Exception ex)
 {
     MessageBox.Show(ex.Message);
 }
 finally
 {
     MessageBox.Show("Data saved successfully...!");
     con.Close();
}

这是创建账户方法的代码：

OleDbDataAdapter adapter = new OleDbDataAdapter("SELECT * from Login", con);
con.Open();

String ticketno = textBox2.Text.ToString();
String Purchaseprice = textBox1.Text.ToString();
String my_query = $"INSERT INTO Login (username, pass) VALUES ('{ticketno}', '{Purchaseprice}')";

OleDbCommand cmd = new OleDbCommand(my_query, con);

cmd.ExecuteNonQuery();

Answer 3

如果您正在使用数据库，则主要使用 try-catch 块语句的帮助，这将帮助并指导您编写代码。在这里，我将向您展示如何使用按钮单击事件在数据库中插入一些值。

 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_query = "INSERT INTO Table1(TicketNo,Sellprice,Purchaseprice)VALUES('"+ticketno+"','"+sellprice+"','"+Purchaseprice+"')";
         
            OleDbCommand cmd = new OleDbCommand(my_query, conn);
            cmd.ExecuteNonQuery();

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

Answer 4

private void btnSave_Click(object sender, EventArgs e)**
{
   OleDbCommand cmd = new OleDbCommand();
   cmd.CommandType = CommandType.Text;
   cmd.CommandText = @"insert into Personal (P_name, P_add,P_Phone)VALUES('" + txtName.Text + "','" +txtAddress.Text + "','" + txtPhone.Text + "')";
   cmd.Connection = con;
   con.Open();
   cmd.ExecuteNonQuery();
   System.Windows.Forms.MessageBox.Show("Recrod Succefully Created");
   con.Close();
   txtName.Text = "";
   txtAddress.Text = "";
   txtPhone.Text = "";
}