How to prevent duplicate record/data entry on page refresh in asp.net

Introduction: In this article i am going to explain How to prevent/avoid/stop duplicate record entry insertion when page is refreshed by clicking on browser's refresh button in asp.net using C# and VB.Net languages.In previous articles i explained How to Disable browser autocomplete feature in TextBox and Retain password value in TextBox after postback and Get browser name,version,type, operating system and Get Title,Description and Keywords Meta tags from URL and Count and display remaining characters in the multiline textbox and Get current page URL/Address  and Create log file to record errors and exceptions.

Description: While developing input forms in Asp.Net many of the developers face a very common issue i.e. insertion of same/duplicate data on refreshing browser by clicking on refresh button or hitting F5. Browser display the above popup message on refreshing page.

Reason: Whenever browser is refreshed it will resend the last request to the website, so when we click on refresh after submitting the record it will insert the new entry of duplicate data in the database.

Solution: we can handle this duplicate insertion of data on browser refresh problem using the three techniques mentioned below: 

1. Redirect to another page after successfully submitting the form.
2. Redirect to same page after successfully submitting the form.
3. Check for already existing duplicate data before submitting record.

 Implementation: Let's discuss 3 these techniques using suitable example. 

• First of all In the Sql server database create the database e.g. "EmpDb" and in this create a table "Tb_Emp" with the Columns and their data types as shown in image below:

Column Name	Data Type
EmpId	Int(Primary Key. So set Is Identity=True
EmpName	varchar(50)
Age	Int
Salary	decimal(18, 0)
Address	varchar(500)

  

• In the web.config file create the connection string as:

 <connectionStrings>

    <add name="conStr" connectionString="Data Source=LALIT;Initial Catalog=EmpDb;Integrated Security=True;Pooling=False"/>

  </connectionStrings>

  <system.web>

Note: Replace the Data Source and Initial Catalog as per your application. 

• In the <Form> tag of design page (.aspx) design the input form as:

HTML Source code

<div>

   <fieldset style="width:300px;">

   <legend>Prevent Duplicate entry on browser refresh</legend>  

    <table>

    <tr>

    <td>Name: </td>

    <td>

        <asp:TextBox ID="txtName" runat="server"></asp:TextBox></td>

    </tr>

    <tr>

    <td>Age: </td>

    <td>

        <asp:TextBox ID="txtAge" runat="server"></asp:TextBox></td>

    </tr>

    <tr>

    <td>Salary</td>

    <td>

        <asp:TextBox ID="txtSalary" runat="server"></asp:TextBox></td>

    </tr>

    <tr>

    <td>Address</td>

    <td>

        <asp:TextBox ID="txtAddress" runat="server" TextMode="MultiLine"></asp:TextBox></td>

    </tr>

    <tr>

    <td></td>

    <td>

        <asp:Button ID="btnSubmit" runat="server" Text="Submit"

            onclick="btnSubmit_Click" />

        </td>

    </tr>

    </table>

   </fieldset>

    </div> 

Redirect to another page after successfully submitting the form.

Suppose you want to show success page e.g. "Successpage.aspx" after record submission then use the code mentioned below

C#.Net Code

protected void btnSubmit_Click(object sender, EventArgs e)

    {

        SqlConnection con = new SqlConnection(ConfigurationManager.ConnectionStrings["conStr"].ConnectionString);

        SqlCommand cmd = new SqlCommand("Insert into Tb_Emp (EmpName,Age,Salary,[Address]) values (@EmpName,@Age,@Salary,@Address)", con);

        cmd.Parameters.AddWithValue("@EmpName", txtName.Text.Trim());

        cmd.Parameters.AddWithValue("@Age", txtAge.Text.Trim());

        cmd.Parameters.AddWithValue("@Salary", txtSalary.Text.Trim());

        cmd.Parameters.AddWithValue("@Address", txtAddress.Text.Trim());

        try

        {

            con.Open();

            cmd.ExecuteNonQuery();

            ScriptManager.RegisterStartupScript(this, this.GetType(), "popup", "alert('Record saved successfully.');window.location='SuccessPage.aspx';", true);

        }

        catch (Exception ex)

        {

            Response.Write("Oops !! Following error occured: " + ex.Message.ToString());

        }

        finally

        {

            con.Close();

            cmd.Dispose();

        }

    }

VB.Net Code

Protected Sub btnSubmit_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles btnSubmit.Click

        Dim con As New SqlConnection(ConfigurationManager.ConnectionStrings("conStr").ConnectionString)

        Dim cmd As New SqlCommand("Insert into Tb_Emp (EmpName,Age,Salary,[Address]) values (@EmpName,@Age,@Salary,@Address)", con)

        cmd.Parameters.AddWithValue("@EmpName", txtName.Text.Trim())

        cmd.Parameters.AddWithValue("@Age", txtAge.Text.Trim())

        cmd.Parameters.AddWithValue("@Salary", txtSalary.Text.Trim())

        cmd.Parameters.AddWithValue("@Address", txtAddress.Text.Trim())

        Try

            con.Open()

            cmd.ExecuteNonQuery()

            ScriptManager.RegisterStartupScript(Me, Me.[GetType](), "popup", "alert('Record saved successfully.');window.location='SuccessPage.aspx';", True)

        Catch ex As Exception

            Response.Write("Oops !! Following error occured: " & ex.Message.ToString())

        Finally

            con.Close()

            cmd.Dispose()

        End Try

    End Sub

Redirect to same page after successfully submitting the form.

Suppose you have input form on the "default page" then redirect to same "default.aspx" after record submission as mentioned below

C#.Net Code

protected void btnSubmit_Click(object sender, EventArgs e)

    {

        SqlConnection con = new SqlConnection(ConfigurationManager.ConnectionStrings["conStr"].ConnectionString);

        SqlCommand cmd = new SqlCommand("Insert into Tb_Emp (EmpName,Age,Salary,[Address]) values (@EmpName,@Age,@Salary,@Address)", con);

        cmd.Parameters.AddWithValue("@EmpName", txtName.Text.Trim());

        cmd.Parameters.AddWithValue("@Age", txtAge.Text.Trim());

        cmd.Parameters.AddWithValue("@Salary", txtSalary.Text.Trim());

        cmd.Parameters.AddWithValue("@Address", txtAddress.Text.Trim());

        try

        {

            con.Open();

            cmd.ExecuteNonQuery();

            ScriptManager.RegisterStartupScript(this, this.GetType(), "popup", "alert('Record saved successfully.');window.location='default.aspx';", true);

        }

        catch (Exception ex)

        {

            Response.Write("Oops !! Following error occured: " + ex.Message.ToString());

        }

        finally

        {

            con.Close();

            cmd.Dispose();

        }

    }

VB.Net Code

Protected Sub btnSubmit_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles btnSubmit.Click

        Dim con As New SqlConnection(ConfigurationManager.ConnectionStrings("conStr").ConnectionString)

        Dim cmd As New SqlCommand("Insert into Tb_Emp (EmpName,Age,Salary,[Address]) values (@EmpName,@Age,@Salary,@Address)", con)

        cmd.Parameters.AddWithValue("@EmpName", txtName.Text.Trim())

        cmd.Parameters.AddWithValue("@Age", txtAge.Text.Trim())

        cmd.Parameters.AddWithValue("@Salary", txtSalary.Text.Trim())

        cmd.Parameters.AddWithValue("@Address", txtAddress.Text.Trim())

        Try

            con.Open()

            cmd.ExecuteNonQuery()

            ScriptManager.RegisterStartupScript(Me, Me.[GetType](), "popup", "alert('Record saved successfully.');window.location='default.aspx';", True)

        Catch ex As Exception

            Response.Write("Oops !! Following error occured: " & ex.Message.ToString())

        Finally

            con.Close()

            cmd.Dispose()

        End Try

    End Sub

Check for already existing duplicate data before submitting record.

The logic is simple. We need to check for the same entry every time before inserting a new record. If the same record is not in the database then it insert the record in the database otherwise not. So we need to create the Stored procedure to perform this.

Note: On refreshing browser it will still show the "Confirm Form Submission" popup message but will not make duplicate entry.

CREATE PROCEDURE [dbo].[SaveEmpRecord_Sp]

                @EmpName     varchar(50),

                @Age                    int,

                @Salary                               decimal(18,0),

                @Address           varchar(500)

AS

BEGIN

                If not exists(select * from Tb_Emp where EmpName=@EmpName and Age=@Age and Salary=@Salary and [Address]=@Address)

                Begin

                                Insert into Tb_Emp (EmpName,Age,Salary,[Address]) values (@EmpName,@Age,@Salary,@Address)

                End

END

C#.Net Code

protected void btnSubmit_Click(object sender, EventArgs e)

    {

        SqlConnection con = new SqlConnection(ConfigurationManager.ConnectionStrings["conStr"].ConnectionString);

        SqlCommand cmd = new SqlCommand("SaveEmpRecord_Sp", con);

        cmd.Parameters.AddWithValue("@EmpName", txtName.Text.Trim());

        cmd.Parameters.AddWithValue("@Age", txtAge.Text.Trim());

        cmd.Parameters.AddWithValue("@Salary", txtSalary.Text.Trim());

        cmd.Parameters.AddWithValue("@Address", txtAddress.Text.Trim());

        cmd.CommandType = CommandType.StoredProcedure;

        try

        {

            con.Open();

            cmd.ExecuteNonQuery();

            ScriptManager.RegisterClientScriptBlock(Page, Page.GetType(), Guid.NewGuid().ToString(), "alert('Record saved successfully');", true);

        }

        catch (Exception ex)

        {

            Response.Write("Oops !! Following error occured: " + ex.Message.ToString());

        }

        finally

        {

            con.Close();

            cmd.Dispose();

        }

    }

VB.Net code

Protected Sub btnSubmit_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles btnSubmit.Click

        Dim con As New SqlConnection(ConfigurationManager.ConnectionStrings("conStr").ConnectionString)

        Dim cmd As New SqlCommand("SaveEmpRecord_Sp", con)

        cmd.Parameters.AddWithValue("@EmpName", txtName.Text.Trim())

        cmd.Parameters.AddWithValue("@Age", txtAge.Text.Trim())

        cmd.Parameters.AddWithValue("@Salary", txtSalary.Text.Trim())

        cmd.Parameters.AddWithValue("@Address", txtAddress.Text.Trim())

        cmd.CommandType = CommandType.StoredProcedure

        Try

            con.Open()

            cmd.ExecuteNonQuery()

            ScriptManager.RegisterClientScriptBlock(Page, Page.[GetType](), Guid.NewGuid().ToString(), "alert('Record saved successfully');", True)

        Catch ex As Exception

            Response.Write("Oops !! Following error occured: " & ex.Message.ToString())

        Finally

            con.Close()

            cmd.Dispose()

        End Try

    End Sub

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