相关疑难解决方法(0)

我对如何从访问数据库获取数据感到困惑.在List中首先收集它然后从列表中获取这些数据是否合适？或者可以直接在数据库中获取它？

我的代码工作得很好,但我想知道是否有更好的方法来做到这一点？:

 private void button3_Click(object sender, EventArgs e)
    {
        OleDbConnection connection = new OleDbConnection(@"Provider=Microsoft.ACE.OLEDB.12.0;Data Source=C:\Users\redgabanan\Desktop\Gabanan_Red_dbaseCon\Red_Database.accdb");
        connection.Open();
        OleDbDataReader reader = null;
        OleDbCommand command = new OleDbCommand("SELECT * from  Users WHERE LastName='"+textBox8.Text+"'", connection);
        reader = command.ExecuteReader();
        listBox1.Items.Clear();

        while (reader.Read())
        {

            listBox1.Items.Add(reader[1].ToString()+","+reader[2].ToString());
        }

        connection.Close();

*我直接从数据库中获取记录,然后将其显示在列表框中.

我有以下方法将数据插入到一个正常工作的访问数据库,但如果我尝试插入包含我所学习的单引号的文本,我确实遇到了问题.

[WebMethod]
public void bookRatedAdd(string title, int rating, string review, string ISBN, string userName)
{
    OleDbConnection conn;
    conn = new OleDbConnection(@"Provider=Microsoft.Jet.OleDb.4.0;
                                               Data Source=" + Server.MapPath("App_Data\\BookRateInitial.mdb"));

    conn.Open();

    OleDbCommand cmd = conn.CreateCommand();

    cmd.CommandText = @"INSERT INTO bookRated([title], [rating],  [review], [frnISBN], [frnUserName])VALUES('" + title + "', '" + rating + "','" + review + "','" + ISBN + "', '" + userName + "')";
    cmd.ExecuteNonQuery();
    conn.Close();
}

据我所知,解决问题的方法之一是使用参数.老实说,我不确定如何做到这一点.我怎么能改变上面的代码,以便我通过使用参数来插入数据？

亲切的问候阿里安

我已经更改了以前的代码,所以我没有使用'使用'.它工作得更早,不同类中的代码基本上代表相同的东西,但它的工作.

我现在盯着它看了2个小时,我无法弄清问题可能出在哪里.

我只有一个阅读器,但每次我使用DisplayFileContent方法时,我收到错误:错误: There is already an open DataReader associated with this command which must be closed first.

// May be public so we can display
// content of file from different forms.
public void DisplayFileContent(string filePath)
{
    // Counting all entries.
    int countEntries = 0;

    // Encrypting/Decrypting  data.
    EncryptDecrypt security = new EncryptDecrypt();

    using (OleDbConnection connection = new OleDbConnection())
    {
        connection.ConnectionString =
            "Provider=Microsoft.ACE.OLEDB.12.0;" +
            "Data Source=" + filePath + ";" +
            "Persist Security Info=False;" +
            "Jet OLEDB:Database Password=" + …

我正在研究数据库管理系统.我有一个更新用户配置文件的简单任务.我创建了一个带有文本框和保存按钮的asp.net页面.添加文本后,单击"保存"按钮.按钮的代码是

protected void Button1_Click(object sender, EventArgs e)
    {
        string firstName = TextBox2.Text;
        string lastName = TextBox1.Text;
        string sCourse = TextBox3.Text;
        string sTelephone = TextBox4.Text;
        string sAddress = TextBox5.Text;
        string sEmail = TextBox6.Text;
        string Gender = TextBox7.Text;
        string user = User.Identity.Name;

        OleDbConnection oleDBConn = new OleDbConnection("Provider=Microsoft.ACE.OLEDB.12.0;Data Source=|DataDirectory|\\ASPNetDB.accdb");
        string sqlQuerry = "UPDATE aspnet_Users SET firstName=@firstName, lastName=@lastName, Gender=@Gender, Address=@Address, Telephone=@Telephone, Course=@Course, Email=@email WHERE UserName=@UserName";

        OleDbCommand cmd = new OleDbCommand(sqlQuerry, oleDBConn);

        cmd.Parameters.AddWithValue("@UserName", User.Identity.Name);
        cmd.Parameters.AddWithValue("@firstName", firstName);
        cmd.Parameters.AddWithValue("@lastName", lastName);
        cmd.Parameters.AddWithValue("@Course", sCourse);
        cmd.Parameters.AddWithValue("@Telephone", sTelephone);
        cmd.Parameters.AddWithValue("@Address", sAddress);
        cmd.Parameters.AddWithValue("@Gender", …