比较2个数据表并得出缺失的数据

Question

我有两个非常相似但有其他列名的数据表。第一个Datatable有4列，大约有7000条记录。第二个也有4列和约37000条记录。现在我想显示第三个数据网格视图中第一个数据表中缺少的记录。我该怎么做？我知道互联网上有很多代码，但没有任何效果。

using Microsoft.Win32; 
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Data.Linq;
using System.Data.OleDb;
using System.Data.Sql;
using System.Data.SqlClient;
using System.Drawing;
using System.IO;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows;
using System.Windows.Forms;
using System.Windows.Input;




namespace Compare
 {
  public partial class Form1 : Form
   {
    public Form1()
    {
        InitializeComponent();
    }


    DataTable ds;
    DataTable dt;

    public void btn_Click(object sender, EventArgs e)
    {
        SqlDataAdapter adapter = new SqlDataAdapter("select a.FALLZAHL, m.CODE, m.ANZ, m.STDAT From test m with (nolock) inner join test2 a with (nolock) on a.id = m.aid where m.STDAT >= '2016-01-01' and m.STALT = '6363' order by a.FALLZAHL", "Server = ada; Database = sd;Trusted_Connection = True");
        ds = new DataTable(" ");
        adapter.Fill(ds);
        dataGridView1.DataSource = ds;



    }

    private void Excelsheet_Click(object sender, EventArgs e)
    {

        openFileDialog1.ShowDialog();




    }

    private void choose_Click(object sender, EventArgs e)
    {
        OpenFileDialog OpenFileDialog = new OpenFileDialog();



    }
    private string Excel03ConString = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source={0};Extended Properties='Excel 8.0;HDR={1}'";

    private string Excel07ConString = "Provider=Microsoft.ACE.OLEDB.12.0;Data Source={0};Extended Properties='Excel 8.0;HDR={0}'";







    public void openFileDialog1_FileOk(object sender, System.ComponentModel.CancelEventArgs e)
    {
        string filePath = openFileDialog1.FileName;

        string extension = Path.GetExtension(filePath);

        string header = radioButton1.Checked ? "YES" : "NO";

        string conStr, sheetName, cells;




        conStr = string.Empty;

        switch (extension)
        {



            case ".xls": //Excel 97-03

                conStr = string.Format(Excel03ConString, filePath, header);

                break;



            case ".xlsx": //Excel 07

                conStr = string.Format(Excel07ConString, filePath, header);

                break;
        }




        using (OleDbConnection con = new OleDbConnection(conStr))
        {

            using (OleDbCommand cmd = new OleDbCommand())
            {

                cmd.Connection = con;
                con.Open();

                System.Data.DataTable dtExcelSchema = con.GetOleDbSchemaTable(OleDbSchemaGuid.Tables, null);

                sheetName = dtExcelSchema.Rows[0]["TABLE_NAME"].ToString();




                con.Close();







            }

        }

        using (OleDbConnection con = new OleDbConnection(conStr))
        {

            using (OleDbCommand cmd = new OleDbCommand())
            {

                using (OleDbDataAdapter oda = new OleDbDataAdapter())
                {

                    dt = new DataTable();

                    cmd.CommandText = "SELECT * From [" + sheetName + "]";

                    cmd.Connection = con;

                    con.Open();

                    oda.SelectCommand = cmd;

                    oda.Fill(dt);

                    con.Close();


                    dataGridView2.DataSource = dt; 


                }

            }

        }
    }



   private void dataGridView3_CellContentClick(object sender, DataGridViewCellEventArgs e)
    {


    }


    private void Form1_Load(object sender, EventArgs e)
    {
        /* dataGridView3.DataSource = from table1 in ds.AsEnumerable()
                      join table2 in dt.AsEnumerable() on table1.Field<int>("ColumnA") equals table2.Field<int>("ColumnA")
                      where table1.Field<int>("ColumnB") == table2.Field<int>("ColumnB") || table1.Field<string>("ColumnC") == table2.Field<string>("ColumnC") || table1.Field<object>("ColumnD") == table2.Field<object>("ColumnD")
                      select table1;
         dataGridView3.DataSource = from table1 in ds.AsEnumerable()
                      where !dataGridView3.Contains(table1)
                      select table1;
         */
    }

    public void CompareData()
    {

    }

    private void button1_Click(object sender, EventArgs e)
    {
        var dsRowCount = ds.AsEnumerable().Count();
        var dtRowCount = dt.AsEnumerable().Count();

        if (dsRowCount > dtRowCount)
        {
            //Set main table to be dt as this has the least number of rows.
            dataGridView3.DataSource = NoMatches(dt, ds);
        }
        else
        {
            //Set main table to ds as this has the least number of rows OR tables have the same number of rows.
            dataGridView3.DataSource = NoMatches(ds, dt);
        }





         }

    private IEnumerable<DataRow> NoMatches(DataTable MainTable, DataTable SecondaryTable)
    {
        var matched = from table1 in MainTable.AsEnumerable()
                      join table2 in SecondaryTable.AsEnumerable()
                      on table1.Field<string>("ISH_FALLZAHL") equals table2.Field<string>("FAL")
                      where (table1.Field<string>("ML_CODE").Equals(table2.Field<string>("LST")))
                     || Convert.ToInt32(table1.Field<Int16>("ML_ANZ")) == Convert.ToInt32(table2.Field<double>("ST"))
                      select table1;

        return MainTable.AsEnumerable().Except(matched);
    }







       // dataGridView3.DataSource = CompareTables();


    }

    /*        public bool DatatablesAreSame()
            {



                if (ds.Rows.Count == dt.Rows.Count)

                    return true;

                foreach (DataColumn dc in ds.Columns)
                {
                    for (int i = 0; i < dt.Rows.Count; i++)
                    {
                        if (ds.Rows[i][dc.ColumnName = "ISH_FALLZAHL"] != dt.Rows[i][dc.ColumnName = "FAL"])
                        {


                        }
                    }
                }

                return true;
            }

       */

/*
    private void CompareTables()
    {

        try
        {



            var dt1Records = ds.AsEnumerable().Select(e1 => new { Id = e1["ISH_FALLZAHL"].ToString(), Name = e1["FAL"].ToString() });

            var dt2Records = dt.AsEnumerable().Select(e2 => new { Id = e2["ISH_FALLZAHL"].ToString(), Name = e2["FAL"].ToString() });



            var extraRecords = dt1Records.Except(dt2Records);




            dataGridView3.DataSource = extraRecords;




        }

        catch (Exception ex)

        { }

    }

  */ 





}

Answer 1

要比较数据集中的2个数据表，您需要实际引用这些表。查看代码时，您似乎正在尝试将已从电子表格填充的数据表连接到整个数据集，这将无法正常工作。

尝试这样的事情：

var matched = from table1 in ds.Tables["Your Table"].AsEnumerable()
              join table2 in dt2.AsEnumerable()
              on table1.Field<string>("ColumnA") equals table2.Field<string>("ColumnC") 
              where (table1.Field<string>("ColumnB").Equals(table2.Field<string>("ColumnA"))) 
              || (table1.Field<int>("ColumnC") == table2.Field<int>("ColumnD")) 
              select table1;

<强> 更新

如果'ds'实际上是一个数据表，那么请进行以下更改：

var matched = from table1 in ds.AsEnumerable()

更新2

根据评论中的图片，映射应该是：

table1.ColumnA = table2.ColumnC - 将其设置为字符串
table1.ColumnB = table2.ColumnA - 将其设置为字符串
table1.ColumnC = table2.ColumnD - 将其设置为int

看起来你应该改变你投射的类型。我已经更新了查询。

更新3

按照我之前的评论尝试从两个数据表中删除案例编号并进行比较。这将告诉您连接是否应返回任何值。为此，您可以使用以下查询：

var dsCaseNumbers = ds.AsEnumerable().Select(x => x.Field<string>("ColumnA").ToList();

这将返回ds中仅包含案例编号的列表。使用dt：

的相同查询创建另一个列表

var dtCaseNumbers = dt.AsEnumerable().Select(x => x.Field<string>("ColumnC").ToList();

然后通过执行以下方式比较2：

var HasMatches = dsCaseNumbers.Any(y => dtCaseNumbers.Contains(y));

如果dsCaseNumbers和dtCaseNumbers之间存在匹配，那么'HasMatches'将为true，否则则为false。

更新4

要仅显示差异，您可以使用以下内容：

var NoMatches = ds.AsEnumerable().Except(matched);

然后，您可以使用“NoMatches”作为另一个数据网格的数据源。如果'NoMatches'由具有最多行的表确定并且不总是'ds'，则将查询包装在一个方法中，该方法采用'main table'参数和'secondary table'参数，如下所示：

private IEnumerable<DataRow> NoMatches (DataTable MainTable, DataTable SecondaryTable)
{
    var matched = from table1 in MainTable.AsEnumerable()
                  join table2 in SecondaryTable.AsEnumerable()
                  on table1.Field<string>("ColumnA") equals table2.Field<string>("ColumnC") 
                  where (table1.Field<string>("ColumnB").Equals(table2.Field<string>("ColumnA"))) 
                  || (table1.Field<int>("ColumnC") == table2.Field<int>("ColumnD")) 
                  select table1;

    return MainTable.AsEnumerable().Except(matched);
}

然后，首先只计算每个表中的行，以确定哪个表应该是主表，并调用上面概述的方法。

更新5

因此，要使用上述方法并在新的数据网格中显示不匹配，您可以执行以下操作：

//First determine which table should be considered 'Main'. This will be the one with the LEAST number of rows.
var dsRowCount = ds.AsEnumerable().Count();
var dtRowCount = dt.AsEnumerable().Count();

if (dsRowCOunt > dtRowCount)
{
    //Set main table to be dt as this has the least number of rows.
    datagridView.Datasource = NoMatches(dt, ds);
}
else
{
    //Set main table to ds as this has the least number of rows OR tables have the same number of rows.
    datagridView.Datasource = NoMatches(ds, dt);
}

更新6

编辑私有IEnumerable NoMatches以返回DataTable，如下所示：

private DataTable NoMatches (DataTable MainTable, DataTable SecondaryTable)
{
    var matched = from table1 in MainTable.AsEnumerable()
                  join table2 in SecondaryTable.AsEnumerable()
                  on table1.Field<string>("ColumnA") equals table2.Field<string>("ColumnC") 
                  where (table1.Field<string>("ColumnB").Equals(table2.Field<string>("ColumnA"))) 
                  || (table1.Field<int>("ColumnC") == table2.Field<int>("ColumnD")) 
                  select table1;

    return MainTable.AsEnumerable().Except(matched).CopyToDataTable();
}

注意2个变化;方法签名和返回使用'CopyToDataTable（）'