如何在C＃中比较2个dataTable

Question

How can I compare the 2 dataTable in c# For example dataTable1

• a,a,a,a,1,a,a,a,a,a
• a,a,a,a,1,a,a,a,a,a
• a,a,a,a,2,a,a,a,a,a
• a,a,a,a,2,a,a,a,a,a
• a,a,a,a,3,a,a,a,a,a

dataTable2

• b,b,b,b,1,b,b,b,b,b
• b,b,b,b,1,b,b,b,b,b
• b,b,b,b,1,b,b,b,b,b
• b,b,b,b,2,b,b,b,b,b
• b,b,b,b,2,b,b,b,b,b

How do I run the 1st row in dataTable1 [5] which is = 1, if dataTable2 [5] also consists 1 then print out the line. Continue until finish. Then Continue loop to second one in dataTable1 check with dataTable2

Here is my code

using System;
using System.Collections.Generic;
using System.Data;
using System.IO;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace CompareLinuxWithWindow
{
    class Program
    {
        static void Main(string[] args)
        {

            DataTable dt1 = ConvertToDataTable(@"C:\Users\manchunl\Desktop\Sample1.txt", 10);
            DataTable dt2 = ConvertToDataTable2(@"C:\Users\manchunl\Desktop\Sample2.txt", 10);

            foreach (DataRow row in dt1.AsEnumerable())
            {
                string temp_dt1 = "";
                string[] words = temp_dt1.Split(',');

                string.Join(",", row.ItemArray.Select(x => x.ToString()));
                temp_Linux = (string.Join(",", row.ItemArray.Select(x => x.ToString())));

            }

            foreach (DataRow row in dt2.AsEnumerable())
            {
                string temp_dt2 = "";

                string.Join(",", row.ItemArray.Select(x => x.ToString()));
                temp_dt2 = (string.Join(",", row.ItemArray.Select(x => x.ToString())));

            }



            Console.WriteLine();
            Console.WriteLine("Press enter to exit.");
            Console.Read();
        }


        public static DataTable ConvertToDataTable(string filePath, int numberOfColumns)
        {


            DataTable tbl = new DataTable();

            for (int col = 0; col < numberOfColumns; col++)
                tbl.Columns.Add(new DataColumn("Column" + (col + 1).ToString()));


            string[] lines = System.IO.File.ReadAllLines(filePath);

            foreach (string line in lines)
            {
                var cols = line.Split(null);

                DataRow dr = tbl.NewRow();
                for (int cIndex = 0; cIndex < numberOfColumns; cIndex++)
                {
                    dr[cIndex] = cols[cIndex];

                }

                tbl.Rows.Add(dr);

            }

            return tbl;
        }

        public static DataTable ConvertToDataTable2(string filePath, int numberOfColumns)
        {


            DataTable tbl = new DataTable();

            for (int col = 0; col < numberOfColumns; col++)
                tbl.Columns.Add(new DataColumn("Column" + (col + 1).ToString()));


            string[] lines = System.IO.File.ReadAllLines(filePath);

            foreach (string line in lines)
            {
                var cols = line.Split(',');

                DataRow dr = tbl.NewRow();
                for (int cIndex = 0; cIndex < numberOfColumns; cIndex++)
                {
                    dr[cIndex] = cols[cIndex];

                }

                tbl.Rows.Add(dr);

            }

            return tbl;
        }
    }
}

Answer 1

You can try using the loop as below, please pay attention to comments as those are important

        // assumption is that both dt1 and dt2 has same number of rows
        // otherise while accessing dt2 we can get index out of range exception
        for (int i = 0; i < dt1.Rows.Count; i++)
        {
            DataRow dr1 = dt1.Rows[i];
            DataRow dr2 = dt2.Rows[i];

            // accessing the column below would return a system.object variable,
            // need to convert it to the right type using one of the convert calls, e.g. Convert.ToInt16(dr1["ColumnName"])
            if (dr1["ColumnName"] == dr2["ColumnName"])
            {
                // do whatever you want to do here
            }
        }

Answer 2

You can return the data table which will be the difference of two input data table and later you can perform operations on the resulting data table.

CODE

    /// <summary>  
    /// Compare two DataTables and return a DataTable with DifferentRecords  
    /// </summary>  
    /// <param name="FirstDataTable">FirstDataTable</param>  
    /// <param name="SecondDataTable">SecondDataTable</param>  
    /// <returns>DifferentRecords</returns>  
    public DataTable getDifferentRecords(DataTable FirstDataTable, DataTable SecondDataTable)
    {
        //Create Empty Table  
        DataTable ResultDataTable = new DataTable("ResultDataTable");
        //use a Dataset to make use of a DataRelation object  
        using (DataSet ds = new DataSet())
        {
            var dataTable = new DataTable[] { FirstDataTable.Copy(), SecondDataTable.Copy() };
            dataTable[0].TableName = "FirstTable";
            dataTable[1].TableName = "SecondTable";
            //Add tables  
            ds.Tables.AddRange(dataTable);
            //Get Columns for DataRelation  
            DataColumn[] firstColumns = new DataColumn[ds.Tables[0].Columns.Count];
            for (int i = 0; i < firstColumns.Length; i++)
            {
                firstColumns[i] = ds.Tables[0].Columns[i];
            }

            DataColumn[] secondColumns = new DataColumn[ds.Tables[1].Columns.Count];
            for (int i = 0; i < secondColumns.Length; i++)
            {
                secondColumns[i] = ds.Tables[1].Columns[i];
            }

            //Create DataRelation  
            DataRelation r1 = new DataRelation(string.Empty, firstColumns, secondColumns, false);
            ds.Relations.Add(r1);
            DataRelation r2 = new DataRelation(string.Empty, secondColumns, firstColumns, false);
            ds.Relations.Add(r2);
            //Create columns for return table  
            for (int i = 0; i < FirstDataTable.Columns.Count; i++)
            {
                ResultDataTable.Columns.Add(FirstDataTable.Columns[i].ColumnName,
                    FirstDataTable.Columns[i].DataType);
            }

            //If FirstDataTable Row not in SecondDataTable, Add to ResultDataTable.  
            ResultDataTable.BeginLoadData();
            foreach (DataRow parentrow in ds.Tables[0].Rows)
            {
                DataRow[] childrows = parentrow.GetChildRows(r1);
                if (childrows == null || childrows.Length == 0)
                {
                    ResultDataTable.LoadDataRow(parentrow.ItemArray, true);
                }
            }

            //If SecondDataTable Row not in FirstDataTable, Add to ResultDataTable.  
            foreach (DataRow parentrow in ds.Tables[1].Rows)
            {
                DataRow[] childrows = parentrow.GetChildRows(r2);
                if (childrows == null || childrows.Length == 0)
                    ResultDataTable.LoadDataRow(parentrow.ItemArray, true);
            }

            ResultDataTable.EndLoadData();
        }

        return ResultDataTable;
    }

Answer 3

1. You need to first loop on the first data table
2. Then get row at specific index
3. Check whether current row exist in second data table
4. Get row from second data table at same index.
5. Read the column value from row to string variable.
6. Check if both value from both row are equal or not.

---

DataTable dt1 = ConvertToDataTable(@"C:\Users\manchunl\Desktop\Sample1.txt", 10);
DataTable dt2 = ConvertToDataTable2(@"C:\Users\manchunl\Desktop\Sample2.txt", 10);

for (int i = 0; i < dt1.Rows.Count; i++)
{
    DataRow dr1 = dt1.Rows[i];

    if (dt2.Rows.Count > i)
    {
        DataRow dr2 = dt2.Rows[i];

        string value1 = Convert.ToString(dr1["Column5"]);
        string value2 = Convert.ToString(dr2["Column5"]);

        if (!string.IsNullOrEmpty(value1) && !string.IsNullOrEmpty(value2) && value1 == value2)
        {
            Console.WriteLine(value1);
        }
        else
        {
            //Do code when no matched.
        }
    }
}