我有測驗代碼,但不確定我如何計算數據庫中問題的總數。我知道我需要一個計數查詢,但我不知道在哪裏插入它。 這裏是我的代碼:獲取錶行數C#
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.Data.OleDb;
using System.Data.Sql;
using System.Data.SqlClient;
namespace Quiz_Test
{
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
}
String chosenAnswer, correctAnswer;
DataTable table;
int questionNumber;
private void Form1_Load(object sender, EventArgs e)
{
string cnString = "Provider=Microsoft.ACE.OLEDB.12.0;Data Source=C:\\Users\\Hannah\\Desktop\\QuizQuestions.accdb";
OleDbConnection conGet = new OleDbConnection(cnString);
OleDbCommand cmdGet = new OleDbCommand();
conGet.Open();
cmdGet.CommandType = CommandType.Text;
cmdGet.Connection = conGet;
cmdGet.CommandText = "SELECT * FROM QuizQuestions ORDER BY rnd()";
OleDbDataReader reader = cmdGet.ExecuteReader();
table = new DataTable();
table.Load(reader);
foreach (DataRow row in table.Rows)
{
labelQuestion.Text = table.Rows[0]["Question"].ToString();
radioButton1.Text = table.Rows[0]["Answer 1"].ToString();
radioButton2.Text = table.Rows[0]["Answer 2"].ToString();
radioButton3.Text = table.Rows[0]["Answer 3"].ToString();
radioButton4.Text = table.Rows[0]["Answer 4"].ToString();
correctAnswer = table.Rows[0]["Correct Answer"].ToString(); ;
questionNumber = 0;
}
conGet.Close();
}
private void btnGoToNextOne_Click(object sender, EventArgs e)
{
String cnString = "Provider=Microsoft.ACE.OLEDB.12.0;Data Source=C:\\Users\\Hannah\\Desktop\\QuizQuestions.accdb";
OleDbConnection conGet = new OleDbConnection(cnString);
OleDbCommand cmdGet = new OleDbCommand();
{
conGet.Open();
cmdGet.CommandType = CommandType.Text;
cmdGet.Connection = conGet;
cmdGet.CommandText = "SELECT * FROM QuizQuestions ORDER BY rnd()";
OleDbDataReader reader = cmdGet.ExecuteReader();
reader.Read();
if (radioButton1.Checked)
{
chosenAnswer = reader["Answer 1"].ToString();
}
else if (radioButton2.Checked)
{
chosenAnswer = reader["Answer 2"].ToString();
}
else if (radioButton3.Checked)
{
chosenAnswer = reader["Answer 3"].ToString();
}
else if (radioButton4.Checked)
{
chosenAnswer = reader["Answer 4"].ToString();
}
if (chosenAnswer == reader["Correct Answer"].ToString())
{
labelQuestion.Text = table.Rows[questionNumber]["Question"].ToString();
//and show possible answers:
radioButton1.Text = table.Rows[questionNumber]["Answer 1"].ToString();
radioButton2.Text = table.Rows[questionNumber]["Answer 2"].ToString();
radioButton3.Text = table.Rows[questionNumber]["Answer 3"].ToString();
radioButton4.Text = table.Rows[questionNumber]["Answer 4"].ToString();
correctAnswer = table.Rows[questionNumber]["Correct Answer"].ToString();
questionNumber++;
}
else
{
MessageBox.Show("That is not the correct answer");
}
}
}
}}
我知道我需要把「從QuizQuestions SELECT COUNT(*)」,但我不知道我怎麼能確定的「位置」在一組問題,使我沒有得到這個錯誤:
IndexOutOfRangeException was unhandled
There is no row at position 5