C# 使用OLEDB连接如何随机化单词

使用OLEDB连接，如何连接Access中包含20个单词的表，然后让它从表中随机选取一个单词并将其存储在表单的标签中

public partial class MainForm : Form
{
    // Use this connection string if your database has the extension .accdb
    private const String access7ConnectionString =
        @"Provider=Microsoft.ACE.OLEDB.12.0;Data Source=|DataDirectory|\WordsDB.accdb";


    // Data components
    private OleDbConnection myConnection;
    private DataTable myDataTable;
    private OleDbDataAdapter myAdapter;
    private OleDbCommandBuilder myCommandBuilder;

    // Index of the current record
    private int currentRecord = 0;


    private void MainForm_Load(object sender, EventArgs e)
    {
        String command = "SELECT * FROM Words";
        try
        {
            myConnection = new OleDbConnection(access7ConnectionString);
            myAdapter = new OleDbDataAdapter(access7ConnectionString, myConnection);
            myCommandBuilder = new OleDbCommandBuilder(myAdapter);
            myDataTable = new DataTable();
            FillDataTable(command);
            DisplayRow(currentRecord);
        }
        catch (Exception ex)
        {
            MessageBox.Show(ex.Message);
        }
    }

    private void FillDataTable(String selectCommand)
    {
        try
        {
            myConnection.Open();
            myAdapter.SelectCommand.CommandText = selectCommand;
            // Fill the datatable with the rows reurned by the select command
            myAdapter.Fill(myDataTable);
            myConnection.Close();
        }
        catch(Exception ex)
        {
            MessageBox.Show("Error in FillDataTable : \r\n" + ex.Message);
        }
    }

    private void DisplayRow(int rowIndex)
    {
        // Check that we can retrieve the given row
        if (myDataTable.Rows.Count == 0)
            return; // nothing to display
        if (rowIndex >= myDataTable.Rows.Count)
            return; // the index is out of range

        // If we get this far then we can retrieve the data
        try
        {
            DataRow row = myDataTable.Rows[rowIndex];
            WordsLbl.Text = row["SpellingWords"].ToString();   
        }
        catch (Exception ex)
        {
            MessageBox.Show("Error in DisplayRow : \r\n" + ex.Message);
        }
    }
}

---

正如您所看到的，这是代码，我试图理解的是，如何从数据库的表中获取一个随机单词并将其存储在标签中？另外，我正在使用OleDbConnection来连接数据库

您可以在

数据表

上使用

一个可计算的

，然后您可以在其中随机选择一个单词。例如，在填充数据表后：

FillDataTable(command); 
var words = myDataTable.AsEnumerable()
     .Select(d => d["word"].ToString())
     .ToList();

Random rnd = new Random();
int randomNumber = rnd.Next(0, words.Count + 1);

string randomWord = words[randomNumber];
label1.Text = randomWord;

---

这应该行得通。您只需在数据库中的以下行中使用您的列名更改

word

。选择（d=>d[“word”].ToString（））在查看我的答案的“拒绝编辑”后，下面是适用于原始问题的部分：

您可以尝试使用“Random”类生成如下所示的随机数：

// =========== Get a Random Number first, then call DisplayRow() ===============

// Figure out the upper range of numbers to choose from the rows returned
int maxCount = myDataTable.Rows.Count;

// generate a random number to use for "rowIndex" in your 'myDataTable.Rows[rowIndex]'
Random randomNR = new Random();
int myRndNR = randomNR.Next(0, maxCount - 1);

// Execute your DisplayRow(int rowIndex) using myRndNR
DisplayRow(myRndNR);

// ===========

private const String access7ConnectionString = @"Provider=Microsoft.ACE.OLEDB.12.0;
Data Source=C:\inetpub\wwwroot\app_data\WordsDB.accdb";

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
using System.Data.OleDb;

namespace WindowsFormsApplication1
{
    public partial class Form1 : Form
    {
        // Use this connection string if your database has the extension .accdb
        private const String access7ConnectionString =
            @"Provider=Microsoft.ACE.OLEDB.12.0;Data Source=C:\inetpub\wwwroot\app_data\WordsDB.accdb";


        // Data components
        private OleDbConnection myConnection;
        private DataTable myDataTable;
        private OleDbDataAdapter myAdapter;
        private OleDbCommandBuilder myCommandBuilder;

        // Index of the current record
        private int currentRecord = 0;

        private void MainForm_Load(object sender, EventArgs e)
        {
            String command = "SELECT * FROM Words";
            try
            {
                myConnection = new OleDbConnection(access7ConnectionString);
                myAdapter = new OleDbDataAdapter(access7ConnectionString, myConnection);
                myCommandBuilder = new OleDbCommandBuilder(myAdapter);
                myDataTable = new DataTable();
                FillDataTable(command);
                /* Move this "DisplayRow(currentRecord);" down below and use 
                   after you get a random number to pick a random word as shown
                   below... */
            }
            catch (Exception ex)
            {
                MessageBox.Show(ex.Message);
            }

// =========== Get a Random Number first, then call DisplayRow() ===============

            // Figure out the upper range of numbers to choose from the rows returned
            int maxCount = myDataTable.Rows.Count;

            // generate a random number to use for "rowIndex" in your 'myDataTable.Rows[rowIndex]'
            Random randomNR = new Random();
            int myRndNR = randomNR.Next(0, maxCount - 1);

            // Execute your DisplayRow(int rowIndex) using myRndNR
            DisplayRow(myRndNR);

// ===========

        }

        private void FillDataTable(String selectCommand)
        {
            try
            {
                myConnection.Open();
                myAdapter.SelectCommand.CommandText = selectCommand;
                // Fill the DataTable with the rows returned by the select command
                myAdapter.Fill(myDataTable);
                myConnection.Close();
            }
            catch (Exception ex)
            {
                MessageBox.Show("Error in FillDataTable : \r\n" + ex.Message);
            }
        }

        private void DisplayRow(int rowIndex)
        {
            // Check that we can retrieve the given row
            if (myDataTable.Rows.Count == 0)
                return; // nothing to display
            if (rowIndex >= myDataTable.Rows.Count)
                return; // the index is out of range

            // If we get this far then we can retrieve the data
            try
            {
                DataRow row = myDataTable.Rows[rowIndex];
                WordsLbl.Text = row["SpellingWords"].ToString();
            }
            catch (Exception ex)
            {
                MessageBox.Show("Error in DisplayRow : \r\n" + ex.Message);
            }
        }
        public Form1()
        {
            InitializeComponent();
        }
    }
}

至于为什么你的计划不起作用（在评论中被问及），我建议如下：

我将您的代码复制并粘贴到一个新项目中，并按照您的描述创建了一个Access数据库。。。我认为你面临的问题是：

问题一：您的程序找不到“WordsDB.accdb”

可能的解决办法：

（1） 您可以找出如何在“连接字符串”中创建正确的| DataDirectory |路径，或者

（2） 将“WordsDB.accdb”放在一个文件夹中，您可以使用如下完整路径“Data Source=C:\inetpub\wwwroot\app\u Data\WordsDB.accdb”引用该文件夹，因此“连接字符串”如下所示：

// =========== Get a Random Number first, then call DisplayRow() ===============

// Figure out the upper range of numbers to choose from the rows returned
int maxCount = myDataTable.Rows.Count;

// generate a random number to use for "rowIndex" in your 'myDataTable.Rows[rowIndex]'
Random randomNR = new Random();
int myRndNR = randomNR.Next(0, maxCount - 1);

// Execute your DisplayRow(int rowIndex) using myRndNR
DisplayRow(myRndNR);

// ===========

private const String access7ConnectionString = @"Provider=Microsoft.ACE.OLEDB.12.0;
Data Source=C:\inetpub\wwwroot\app_data\WordsDB.accdb";

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
using System.Data.OleDb;

namespace WindowsFormsApplication1
{
    public partial class Form1 : Form
    {
        // Use this connection string if your database has the extension .accdb
        private const String access7ConnectionString =
            @"Provider=Microsoft.ACE.OLEDB.12.0;Data Source=C:\inetpub\wwwroot\app_data\WordsDB.accdb";


        // Data components
        private OleDbConnection myConnection;
        private DataTable myDataTable;
        private OleDbDataAdapter myAdapter;
        private OleDbCommandBuilder myCommandBuilder;

        // Index of the current record
        private int currentRecord = 0;

        private void MainForm_Load(object sender, EventArgs e)
        {
            String command = "SELECT * FROM Words";
            try
            {
                myConnection = new OleDbConnection(access7ConnectionString);
                myAdapter = new OleDbDataAdapter(access7ConnectionString, myConnection);
                myCommandBuilder = new OleDbCommandBuilder(myAdapter);
                myDataTable = new DataTable();
                FillDataTable(command);
                /* Move this "DisplayRow(currentRecord);" down below and use 
                   after you get a random number to pick a random word as shown
                   below... */
            }
            catch (Exception ex)
            {
                MessageBox.Show(ex.Message);
            }

// =========== Get a Random Number first, then call DisplayRow() ===============

            // Figure out the upper range of numbers to choose from the rows returned
            int maxCount = myDataTable.Rows.Count;

            // generate a random number to use for "rowIndex" in your 'myDataTable.Rows[rowIndex]'
            Random randomNR = new Random();
            int myRndNR = randomNR.Next(0, maxCount - 1);

            // Execute your DisplayRow(int rowIndex) using myRndNR
            DisplayRow(myRndNR);

// ===========

        }

        private void FillDataTable(String selectCommand)
        {
            try
            {
                myConnection.Open();
                myAdapter.SelectCommand.CommandText = selectCommand;
                // Fill the DataTable with the rows returned by the select command
                myAdapter.Fill(myDataTable);
                myConnection.Close();
            }
            catch (Exception ex)
            {
                MessageBox.Show("Error in FillDataTable : \r\n" + ex.Message);
            }
        }

        private void DisplayRow(int rowIndex)
        {
            // Check that we can retrieve the given row
            if (myDataTable.Rows.Count == 0)
                return; // nothing to display
            if (rowIndex >= myDataTable.Rows.Count)
                return; // the index is out of range

            // If we get this far then we can retrieve the data
            try
            {
                DataRow row = myDataTable.Rows[rowIndex];
                WordsLbl.Text = row["SpellingWords"].ToString();
            }
            catch (Exception ex)
            {
                MessageBox.Show("Error in DisplayRow : \r\n" + ex.Message);
            }
        }
        public Form1()
        {
            InitializeComponent();
        }
    }
}

问题二：您需要将随机代码移出当前位置，以便在填充数据表后执行它

可能的解决办法：

（1） 将Form1.cs更改为如下所示：

// =========== Get a Random Number first, then call DisplayRow() ===============

// Figure out the upper range of numbers to choose from the rows returned
int maxCount = myDataTable.Rows.Count;

// generate a random number to use for "rowIndex" in your 'myDataTable.Rows[rowIndex]'
Random randomNR = new Random();
int myRndNR = randomNR.Next(0, maxCount - 1);

// Execute your DisplayRow(int rowIndex) using myRndNR
DisplayRow(myRndNR);

// ===========

private const String access7ConnectionString = @"Provider=Microsoft.ACE.OLEDB.12.0;
Data Source=C:\inetpub\wwwroot\app_data\WordsDB.accdb";

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
using System.Data.OleDb;

namespace WindowsFormsApplication1
{
    public partial class Form1 : Form
    {
        // Use this connection string if your database has the extension .accdb
        private const String access7ConnectionString =
            @"Provider=Microsoft.ACE.OLEDB.12.0;Data Source=C:\inetpub\wwwroot\app_data\WordsDB.accdb";


        // Data components
        private OleDbConnection myConnection;
        private DataTable myDataTable;
        private OleDbDataAdapter myAdapter;
        private OleDbCommandBuilder myCommandBuilder;

        // Index of the current record
        private int currentRecord = 0;

        private void MainForm_Load(object sender, EventArgs e)
        {
            String command = "SELECT * FROM Words";
            try
            {
                myConnection = new OleDbConnection(access7ConnectionString);
                myAdapter = new OleDbDataAdapter(access7ConnectionString, myConnection);
                myCommandBuilder = new OleDbCommandBuilder(myAdapter);
                myDataTable = new DataTable();
                FillDataTable(command);
                /* Move this "DisplayRow(currentRecord);" down below and use 
                   after you get a random number to pick a random word as shown
                   below... */
            }
            catch (Exception ex)
            {
                MessageBox.Show(ex.Message);
            }

// =========== Get a Random Number first, then call DisplayRow() ===============

            // Figure out the upper range of numbers to choose from the rows returned
            int maxCount = myDataTable.Rows.Count;

            // generate a random number to use for "rowIndex" in your 'myDataTable.Rows[rowIndex]'
            Random randomNR = new Random();
            int myRndNR = randomNR.Next(0, maxCount - 1);

            // Execute your DisplayRow(int rowIndex) using myRndNR
            DisplayRow(myRndNR);

// ===========

        }

        private void FillDataTable(String selectCommand)
        {
            try
            {
                myConnection.Open();
                myAdapter.SelectCommand.CommandText = selectCommand;
                // Fill the DataTable with the rows returned by the select command
                myAdapter.Fill(myDataTable);
                myConnection.Close();
            }
            catch (Exception ex)
            {
                MessageBox.Show("Error in FillDataTable : \r\n" + ex.Message);
            }
        }

        private void DisplayRow(int rowIndex)
        {
            // Check that we can retrieve the given row
            if (myDataTable.Rows.Count == 0)
                return; // nothing to display
            if (rowIndex >= myDataTable.Rows.Count)
                return; // the index is out of range

            // If we get this far then we can retrieve the data
            try
            {
                DataRow row = myDataTable.Rows[rowIndex];
                WordsLbl.Text = row["SpellingWords"].ToString();
            }
            catch (Exception ex)
            {
                MessageBox.Show("Error in DisplayRow : \r\n" + ex.Message);
            }
        }
        public Form1()
        {
            InitializeComponent();
        }
    }
}

潜在问题：

您的表单可能没有要执行的“事件、行为、加载”集合

MainForm_Load

潜在解决方案：

a。转到Visual Studio中的“设计”视图，然后右键单击表单

b。单击弹出窗口上的“属性”

c。在“属性”窗口（可能在Visual Studio的右下角）中查找“事件”

d。找到“事件”后，查找“行为”（如果按“类别”对属性排序）或“加载”（如果按字母顺序对属性排序）

---

e。在“加载”框中，确保它显示“MainForm_Load”

因为您使用的是access，这是您在数据表中填充行后可以执行的操作。在填充数据表之后，我已经能够测试这一点。我从另一个数据库填充了我的datatable，但这并不重要。我的代码的最后4行帮助您每次从datatable中获得一条随机记录

{
    const string query = "SELECT name FROM NewTable";
    var command = new SqlCommand(){CommandText = query, CommandType = System.Data.CommandType.Text,Connection=sqlConn};
    var dataAdapter = new SqlDataAdapter() { SelectCommand = command };
    DataTable dataTable = new DataTable("Names");
    dataAdapter.Fill(dataTable);

    int count = dataTable.Rows.Count; 
    int index = new Random().Next(count);

    DataRow d = dataTable.Rows[index];
    Console.WriteLine(d[0]);

}

---

你试过什么了吗？当您已经开始时，帮助会更容易。@gunr2171开始了，很抱歉谢谢您的回答它没有错误，但是随机单词没有显示在标签中。表格加载时正在填充，您没有收到任何错误，对吗？表单加载并运行后，实际数据库中的最后一个“拼写单词”是否作为您的“单词BL”出现在表单上？没有。。没有字在工作，你能解释一下你在那里做的一切吗？因为它在工作，我假设你知道如何创建一个有效的连接字符串到你的数据库（WordsDB.accdb），并验证了“MainForm_Load”在你运行程序时被调用。。。我所做的唯一真正的更改是将“DisplayRow（currentRecord）；”方法移动到数据集和数据表填充后运行。请看我上面的例子中关于“DisplayRow”的评论。好的，我不明白，谢谢你的回答。顺便说一句，我真的很感激。。也就是说，如果我有一个“go”按钮，你如何让它变成另一个随机单词并存储在标签中？