Merge two DataTables in C#

In this post, I am sharing how Merge() method is used to merge two DataTables in C# / ASP.Net

There are certain points need to be considered when using Merge() method to merge datatables.

Let's assume there are 2 datatables and we have to merge both the datatables on the basis of Employee Id then,

  • Both the DataTable should have a column with the same name say "EmpId".
  • Values in columns "EmpId" of both the tables should be unique.

MergeTable.aspx Code
<%@ Page Language="C#" AutoEventWireup="true" CodeFile="MergeTable.aspx.cs" Inherits="MergeTable" %>
<html>
<head runat="server">
    <title>Merge Two DataTables</title>
</head>
<body>
    <form id="form1" runat="server">
    <div>
        <asp:GridView ID="GridView1" runat="server"></asp:GridView>
    </div>
    </form>
</body>
</html>

MergeTable.aspx.cs
using System;
using System.Data;

public partial class MergeTable : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {
        if (!IsPostBack)
        {
            DataTable dataTable1 = null, dataTable2 = null, dataTable3 = null;
            dataTable1 = DataTable1();
            dataTable2 = DataTable2();
            dataTable1.PrimaryKey = new DataColumn[] { dataTable1.Columns["EmpId"] };
            dataTable2.PrimaryKey = new DataColumn[] { dataTable2.Columns["EmpId"] };
            dataTable3 = dataTable1.Copy();
            dataTable3.Merge(dataTable2, false, MissingSchemaAction.Add);
            dataTable3.AcceptChanges();
            GridView1.DataSource = dataTable3;
            GridView1.DataBind();
        }
    }

    private DataTable DataTable1()
    {
        DataRow dataRow = null;
        DataTable dt1 = new DataTable();
        dt1.Columns.Add("EmpId");
        dt1.Columns.Add("EmpName");
        dataRow = dt1.NewRow();
        dataRow["EmpId"] = "EMP001";
        dataRow["EmpName"] = "Ajaj Kumar";
        dt1.Rows.Add(dataRow);
        dataRow = dt1.NewRow();
        dataRow["EmpId"] = "EMP002";
        dataRow["EmpName"] = "Sanjay Gupta";
        dt1.Rows.Add(dataRow);
        dt1.AcceptChanges();
        return dt1;
    }

    private DataTable DataTable2()
    {
        DataRow dr = null;
        DataTable dt2 = new DataTable();
        dt2.Columns.Add("EmpId");
        dt2.Columns.Add("Salary");
        dr = dt2.NewRow();
        dr["EmpId"] = "EMP001";
        dr["Salary"] = "50000";
        dt2.Rows.Add(dr);
        dr = dt2.NewRow();
        dr["EmpId"] = "EMP002";
        dr["Salary"] = "45000";
        dt2.Rows.Add(dr);
        dt2.AcceptChanges();
        return dt2;
    }
}

I am a Software Engineer and passionate programmer. Love working in SQL Server. Like participating in online technical communities like asp.net, MSDN, technical discussions and helping my friends, colleagues and others in their technical problems

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