如何使用 C# 從 SQL Server 隨機檢索數據

Question

我的數據庫中有一組問題，每次都需要以隨機順序檢索它們。

有人可以幫我解決 C# 代碼嗎？ 我正在使用 Visual Studio 2012。

提前致謝。

這是我目前使用的代碼：

using System;
using System.Data;
using System.Configuration;
using System.Collections;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;

public partial class perform_test : System.Web.UI.Page
{
public int CurrentPage
{
    get
    {
        object o = this.ViewState["_CurrentPage"];
        if (o == null)
            return 0;
        else
            return (int)o;
    }

    set
    {
        this.ViewState["_CurrentPage"] = value;
    }
}

protected void Page_Load(object sender, EventArgs e)
{


    //Response.Write(Session["Company"]);
    if (!Page.IsPostBack)
    {
        Session.Add("CorrectAnswers", 0);
       //Session.Add("Questions", 0);
        Session.Add("Answer", "");

    }
    if (repeat_exam_data.Controls.Count > 0)
    {
        for (int i = 1; i <= 4; i++)
        {
            RadioButton rad = repeat_exam_data.Controls[0].FindControl("Choice" + i.ToString()) as RadioButton;
            if (rad.Checked)
            {
                Session["Answer"] = rad.Text;
                break;
            }
        }
    }

    GetPage();
}

protected void GetPage()
{
    DataTable exam_data = new DataTable();

    exam_data = BussinessLayer.GetExamData(Session["Company"].ToString(), Session["Subject"].ToString(), Session["ExamId"].ToString());
    PagedDataSource pgds = new PagedDataSource();
    pgds.DataSource = exam_data.DefaultView;
    pgds.AllowPaging = true;
    pgds.PageSize = 1;

    pgds.CurrentPageIndex = CurrentPage;

    repeat_exam_data.DataSource = pgds;
    repeat_exam_data.DataBind();

    Cmd_Next.Enabled = !pgds.IsLastPage;
    Cmd_Finish.Enabled = pgds.IsLastPage;
    lblQno.Text = Convert.ToString((CurrentPage + 1));
    lblCorrectAnswers.Text = Session["CorrectAnswers"].ToString();
}
protected void Cmd_Next_Click(object sender, EventArgs e)
{

    CalculateMark();

    CurrentPage += 1;
    GetPage();
}
protected void Cmd_Finish_Click(object sender, EventArgs e)
{
    CalculateMark();

    string strSql = "INSERT INTO tbl_result(ExamId,StudentId,Mark) VALUES('" + Session["ExamId"] + "','" + Session["uname"] + "','" + Session["CorrectAnswers"] + "')";
    BussinessLayer.PutData(strSql);
    Response.Redirect("~/canexamresult.aspx");
}

private void CalculateMark()
{
    HiddenField ans = repeat_exam_data.Controls[0].FindControl("Answer") as     HiddenField;
    if (Session["Answer"].ToString() == ans.Value)
        Session["CorrectAnswers"] = (int)Session["CorrectAnswers"] + 1;

}
}

Answer 1

此代碼不包含負責獲取數據的代碼。 它可能在 BussinessLayer.GetExamData() 內。 例如，您可以使用

ORDER BY NEWID()

在查詢結束時。

Answer 2

您可以使用

ORDER BY NEWID();

正如 Sleipneir 建議的那樣，或者將整個數據集加載到一個列表中，然后以隨機方式吃掉該列表。