Sunday, April 8, 2012

merge 2 datatables in c#


In this post, I am sharing how Merge() method is used to merge two datatables. 

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 Code
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;
    }
}

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