Check UserName Email Availability In Asp.Net Ajax

This example explains how to Check Email Or UserName Availability Using Ajax In Asp.Net C# VB.

You may also like to read one of my previous posts where i described how to Create User Registration Form.

For this create a table Users in sql server database with ID,Uname,emlAddress columns and add some records in it.

Add ScriptManager,Ajax UpdatePanel on the page, and inside ContentTemplate place two textbox, two image control to display images and two label controls for related messages.

Set AutoPostBack property of textbox to true.

HTML SOURCE OF PAGE

---

   1:  <asp:ScriptManager ID="ScriptManager1" runat="server"/>

   2:  <asp:UpdatePanel ID="UpdatePanel1" runat="server">

   3:  <ContentTemplate>

   4:      UserName: 

   5:      <asp:TextBox ID="txtUName" runat="server" 

   6:                   ontextchanged="txtUName_TextChanged" 

   7:                   AutoPostBack="True"/>

   8:      

   9:      <asp:Image ID="imgUsr" runat="server" Visible="false"/>

  10:      <asp:Label ID="lblUsr" runat="server"/>

  11:      

  12:      Email ID:

  13:      <asp:TextBox ID="txtId" runat="server" 

  14:                   AutoPostBack="True" 

  15:                   ontextchanged="txtId_TextChanged"/>

  16:      <asp:Image ID="imgId" runat="server" Visible="false"/>

  17:      <asp:Label ID="lblId" runat="server"></asp:Label>

  18:  </ContentTemplate>

  19:  </asp:UpdatePanel>

Write below mentioned code in TextChanged Event of textbox

C# CODE

---

show source

01protected void txtUName_TextChanged(object sender, EventArgs e)

02    {

03        if (txtUName.Text != string.Empty)

04        {

05            string strConnection = ConfigurationManager.ConnectionStrings["ConnectionString"].ConnectionString;

06            string strSelect = "SELECT COUNT(*) FROM Users WHERE Uname = @Username";

07            SqlConnection con = new SqlConnection(strConnection);

08            SqlCommand cmd = new SqlCommand(strSelect,con);

09 

10            SqlParameter user = new SqlParameter("@Username", SqlDbType.VarChar);

11            user.Value = txtUName.Text.Trim().ToString();

12            cmd.Parameters.Add(user);

13            con.Open();

14            int result = (Int32)cmd.ExecuteScalar();

15            con.Close();

16 

17            if (result >= 1)

18            {

19                imgUsr.ImageUrl = "unavailable.png";

20                imgUsr.Visible = true;

21                lblUsr.Text = "Username not available";

22                lblUsr.ForeColor = System.Drawing.Color.Red;

23            }

24            else

25            {

26                imgUsr.ImageUrl = "tick.png";

27                imgUsr.Visible = true;

28                lblUsr.Text = "Available";

29                lblUsr.ForeColor = System.Drawing.Color.Green;

30            }

31        }

32 

33    }

VB.NET CODE

---

show source

01Protected Sub txtUName_TextChanged(sender As Object, e As EventArgs)

02 If txtUName.Text <> String.Empty Then

03  Dim strConnection As String = ConfigurationManager.ConnectionStrings("ConnectionString").ConnectionString

04  Dim strSelect As String = "SELECT COUNT(*) FROM Users WHERE Uname = @Username"

05  Dim con As New SqlConnection(strConnection)

06  Dim cmd As New SqlCommand(strSelect, con)

07 

08  Dim user As New SqlParameter("@Username", SqlDbType.VarChar)

09  user.Value = txtUName.Text.Trim().ToString()

10  cmd.Parameters.Add(user)

11  con.Open()

12  Dim result As Integer = DirectCast(cmd.ExecuteScalar(), Int32)

13  con.Close()

14 

15  If result >= 1 Then

16   imgUsr.ImageUrl = "unavailable.png"

17   imgUsr.Visible = True

18   lblUsr.Text = "Username not available"

19   lblUsr.ForeColor = System.Drawing.Color.Red

20  Else

21   imgUsr.ImageUrl = "tick.png"

22   imgUsr.Visible = True

23   lblUsr.Text = "Available"

24   lblUsr.ForeColor = System.Drawing.Color.Green

25  End If

26 End If

27 

28End Sub

Similarly we can check email availability by writing following code

show source

01protected void txtId_TextChanged(object sender, EventArgs e)

02    {

03        if (txtId.Text != string.Empty)

04        {

05            string strConnection = ConfigurationManager.ConnectionStrings["ConnectionString"].ConnectionString;

06            string strSelect = "SELECT COUNT(*) FROM Users WHERE emlAddress = @Email";

07            SqlConnection con = new SqlConnection(strConnection);

08            SqlCommand cmd = new SqlCommand(strSelect, con);

09            cmd.Parameters.AddWithValue("@Email", txtId.Text.Trim().ToString());

10 

11            con.Open();

12            int result = (Int32)cmd.ExecuteScalar();

13            con.Close();

14 

15            if (result >= 1)

16            {

17                imgId.ImageUrl = "unavailable.png";

18                imgId.Visible = true;

19                lblId.Text = "Email already registered";

20                lblId.ForeColor = System.Drawing.Color.Red;

21            }

22            else

23            {

24                imgId.ImageUrl = "tick.png";

25                imgId.Visible = true;

26                lblId.Text = "Available";

27                lblId.ForeColor = System.Drawing.Color.Green;

28            }

29        }

30    }

Download Sample Code

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