Check if a particular value exists in DataTable (DataSet) using C# .Net

try like this :

DataRow[] rows = dt.Select("Your Data Table Field ='" + What You want to find + "'");
if(rows.Length > 0) { Response.Write("Exists");

example : if you have bat field in datatable and you want to find the bat's name then do this :

string batName = "Gray Nickels";
DataRow[] rows = dt.Select("bat='" + batName  + "'");
if(rows.Length > 0) { Response.Write("Exists");   

if u wish to update then do this instead of response.write :

var dt = ViewState["PPDataTable"] as DataTable; dt["id"] = "Changed"; ViewState["PPDataTable"] = dt;

Hi P@v@n,

 Please refer below Sample.

HTML

<div>
    Search Id:<asp:TextBox ID="txtSearchId" Text="1" runat="server" />
    <br />
    Update value:<asp:TextBox ID="txtUpdateValue" Text="7" runat="server" />
    <br />
    <asp:Button Text="Search and Update value" runat="server" OnClick="SearchAndUpdate" />
</div>
<hr />
<asp:GridView ID="GridView1" runat="server" />

Namespace

C#

using System.Data;

VB.Net

Imports System.Data

Code

C#

protected void SearchAndUpdate(object sender, EventArgs e)
{
    DataTable dt = new DataTable();
    dt.Columns.AddRange(
        new DataColumn[3] {
        new DataColumn("Id", typeof(int)),
        new DataColumn("Name", typeof(string)),
        new DataColumn("Country",typeof(string)) });

    dt.Rows.Add(1, "John Hammond", "United States");
    dt.Rows.Add(2, "Mudassar Khan", "India");
    dt.Rows.Add(3, "Suzanne Mathews", "France");
    dt.Rows.Add(4, "Robert Schidner", "Russia");
    DataSet ds = new DataSet();
    ds.Tables.Add(dt);
    int rowsCount = 0;
    foreach (DataRow row in ds.Tables[0].Rows)
    {
        if (row["Id"].ToString() == this.txtSearchId.Text.Trim())
        {
            row["Id"] = this.txtUpdateValue.Text.Trim();
        }
        else
        {
            rowsCount++;
        }
    }
    if (rowsCount == ds.Tables[0].Rows.Count)
    {
        ClientScript.RegisterStartupScript(this.GetType(), "alert", "alert('No Id Found')", true);
    }

    this.GridView1.DataSource = ds;
    this.GridView1.DataBind();
}

VB.Net

Protected Sub SearchAndUpdate(ByVal sender As Object, ByVal e As EventArgs)
    Dim dt As DataTable = New DataTable()
    dt.Columns.AddRange(New DataColumn(2) {New DataColumn("Id", GetType(Integer)), New DataColumn("Name", GetType(String)), New DataColumn("Country", GetType(String))})
    dt.Rows.Add(1, "John Hammond", "United States")
    dt.Rows.Add(2, "Mudassar Khan", "India")
    dt.Rows.Add(3, "Suzanne Mathews", "France")
    dt.Rows.Add(4, "Robert Schidner", "Russia")
    Dim ds As DataSet = New DataSet()
    ds.Tables.Add(dt)
    Dim rowsCount As Integer = 0

    For Each row As DataRow In ds.Tables(0).Rows

        If row("Id").ToString() = Me.txtSearchId.Text.Trim() Then
            row("Id") = Me.txtUpdateValue.Text.Trim()
        Else
            rowsCount += 1
        End If
    Next

    If rowsCount = ds.Tables(0).Rows.Count Then
        ClientScript.RegisterStartupScript(Me.GetType(), "alert", "alert('No Id Found')", True)
    End If

    Me.GridView1.DataSource = ds
    Me.GridView1.DataBind()
End Sub

Screenshot