如何在c#中打乱Datatable的特定列

Question

我正在使用 MS Access 数据库开发 C# 中的考试试卷匹配模块。这里有一个与匹配模块相关的问题：我有一个如下所示的数据表，我想以随机播放的形式调用匹配模块。

Q_id           Question           Question_type         MatchA      MatchB    Std  sub 

 1         Where is Lion live?       Ques_Ans                                   1  eng                                             
 2         What is sun ?             Ques_Ans                                   1  eng   
 3             NULL                  Matching          Lion       Den           1  eng
 4             NULL                  Matching          Hen        Coop          1  eng
 5             NULL                  Matching          Rabbit     Burrow        1  eng
 6             NUll                  Matching          Earth      Planet        2  Sci

问题在报告中正确打印但卡在匹配中。

我执行以下查询。

查询

Select * 
from Question_table 
where std = 1 and sub = "eng" 

水晶报表输出：

Match the following :

    1.Lion          Den
    2.hen           Coop
    3.Rabbit        Burrow

但我想要一个匹配的输出：

Match the following :

1.Lion          Burrow
2.hen           Den
3.Rabbit        Coop

我的问题是如何在特定 1 列 (MatchB) 的 C# 代码中对数据表进行洗牌？所以它会像上面那样在 Crystal Reports 中打印出来。

Answer 1

试试这个

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Data;

namespace ConsoleApplication1
{
    class Program
    {
        static void Main(string[] args)
        {
            DataTable dt = new DataTable();

            dt.Columns.Add("Q_id", typeof(int));
            dt.Columns.Add("Question", typeof(string));
            dt.Columns.Add("Question_type", typeof(string));
            dt.Columns.Add("MatchA", typeof(string));
            dt.Columns.Add("MatchB", typeof(string));
            dt.Columns.Add("Std", typeof(int));
            dt.Columns.Add("sub", typeof(string));

            dt.Rows.Add(new object[] { 1, "Where is Lion live?", "Ques_Ans", null, null, 1, "eng"});
            dt.Rows.Add(new object[] { 2, "What is sun ?", "Ques_Ans", null, null, 1, "eng"});
            dt.Rows.Add(new object[] { 3, null, "Matching", "Lion", "Den", 1, "eng"});
            dt.Rows.Add(new object[] { 4, null, "Matching", "Hen", "Coop", 1, "eng"});
            dt.Rows.Add(new object[] { 5, null, "Matching", "Rabbit", "Burrow", 1, "eng"});
            dt.Rows.Add(new object[] { 6, null, "Matching", "Earth", "Planet", 2, "Sci"});

            List<DataRow> questions = dt.AsEnumerable().Where(x => x.Field<string>("Question_type") == "Ques_Ans").ToList();

            List<DataRow> answers = dt.AsEnumerable().Where(x => x.Field<string>("Question_type") == "Matching").ToList();

            Random rand = new Random();
            foreach(DataRow question in questions)
            {
                List<DataRow> questionAnswers = answers.Where(x => x.Field<int>("Std") == question.Field<int>("Q_id")).ToList();

                //create random list of Match B

                var randB = questionAnswers.Select(x => new { B = x.Field<string>("MatchB"), rand = rand.Next() }).OrderBy(x => x.rand).ToList();
                Console.WriteLine("Question {0}", question.Field<string>("Question"));
                for(int i = 0; i < questionAnswers.Count; i++)
                {
                    Console.WriteLine("{0}. {1}     {2}", i + 1, questionAnswers[i].Field<string>("MatchA"), randB[i].B);
                }
            }
            Console.ReadLine();

        }
    }
}

Answer 2

谢谢。现在我得到了答案，也想和这个网站分享。

     int cnt_match = ds.Tables[0].Select("Question_type = Matching").Length; //Count the numbers of row which having question matching .
            int count = 0;
            int min = 0;
            int max = 0;
//Make a list of random number 
            List<int> list_rno = new List<int>(); //random number list array 
            if (cnt_match > 0)
            {
                //- shuffling the match B ---> Start
                Random rand = new Random();
                for (int i = 0; i <= ds.Tables[0].Rows.Count - 1; i++)
                {
                    string que_type = ds.Tables[0].Rows[i]["Question_Type"].ToString();
                    if (que_type == "Matching") 
                    {
                        if (count == 0)
                        {
                            max = i + cnt_match;     //Last row of dataset of matching question 
                            min = i;  //First row no of Dataset of matching question 
                            list_rno = GetRandomNumbers(min, max);
                        }
                        if (count < cnt_match)
                        {
                            //swapping the value <--start-->
                            string temp = ds.Tables[0].Rows[i]["MatchB"].ToString();
                            ds.Tables[0].Rows[i]["MatchB"] = ds.Tables[0].Rows[list_rno[count]]["MatchB"].ToString();
                            ds.Tables[0].Rows[list_rno[count]]["MatchB"] = temp;
                            //swaping the value <--end-->
                            count++;
                        }
                        else
                        {
                            break;
                        }
                    }
                }

随机函数，生成从最小值到最大值的数字，并且只调用一次

 static Random random = new Random();
        public static List<int> GetRandomNumbers(int min, int max)
        {
            List<int> randomNumbers = new List<int>();
            for (int i = min; i < max; i++)
            {
                int number;
                do
                {
                    number = random.Next(min, max);
                }
                while (randomNumbers.Contains(number));
                randomNumbers.Add(number);
            }
            return randomNumbers;
        }