How to Check UserName Email Availability In Asp.Net Using Ajax

Check Username or Email availability in asp.net using Ajax C# and VB.Net


In this post i'm explaining how to check username or email availability using ajax in asp.net user registration page.

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

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

Drag and Place ScriptManager and Ajax UpdatePanel on the page, and inside ContentTemplate of update panel place two textbox for username and email, two image control to display images and two label control to display related messages.


Set AutoPostBack property of textbox to true.

HTML SOURCE OF PAGE

---

   1:  <form id="form1" runat="server">

   2:  <div>

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

   4:  </div>

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

   6:  <ContentTemplate>

   7:  <table><tr><td>UserName: </td>

   8:  <td>

   9:  <asp:TextBox ID="txtUserName" runat="server" 

  10:               ontextchanged="txtUserName_TextChanged" 

  11:               AutoPostBack="True">

  12:  </asp:TextBox></td>

  13:  <td>

  14:  <asp:Image ID="imgUser" runat="server" Visible="false"/>

  15:  </td>

  16:  <td><asp:Label ID="lblUser" runat="server"/></td></tr>

  17:   

  18:  <tr><td>Email ID: </td>

  19:  <td>

  20:  <asp:TextBox ID="txtEmail" runat="server" 

  21:               AutoPostBack="True" 

  22:               ontextchanged="txtEmail_TextChanged">

  23:  </asp:TextBox></td>

  24:  <td>

  25:  <asp:Image ID="imgEmail" runat="server" Visible="false"/>

  26:  </td>

  27:  <td><asp:Label ID="lblEmail" runat="server"/></td></tr>

  28:  </table>

  29:  </ContentTemplate>

  30:  </asp:UpdatePanel>

  31:  </form>

Write below mentioned code in TextChanged Event of Username textbox

C# CODE

---

01protected void txtUserName_TextChanged(object sender, EventArgs e)

02    {

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

04        {

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

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

07            SqlConnection con = new SqlConnection(strConnection);

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

09 

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

11            username.Value = txtUserName.Text.Trim().ToString();

12            cmd.Parameters.Add(username);

13            con.Open();

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

15            con.Close();

16 

17            if (result >= 1)

18            {

19                imgUser.ImageUrl = "unavailable.png";

20                imgUser.Visible = true;

21                lblUser.Text = "Username not available";

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

23            }

24            else

25            {

26                imgUser.ImageUrl = "tick.png";

27                imgUser.Visible = true;

28                lblUser.Text = "Available";

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

30            }

31        }

32    }

VB.NET CODE

---

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

02 If txtUserName.Text <> String.Empty Then

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

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

05  Dim con As New SqlConnection(strConnection)

06  Dim cmd As New SqlCommand(strSelect, con)

07 

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

09  username.Value = txtUserName.Text.Trim().ToString()

10  cmd.Parameters.Add(username)

11  con.Open()

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

13  con.Close()

14 

15  If result >= 1 Then

16   imgUser.ImageUrl = "unavailable.png"

17   imgUser.Visible = True

18   lblUser.Text = "Username not available"

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

20  Else

21   imgUser.ImageUrl = "tick.png"

22   imgUser.Visible = True

23   lblUser.Text = "Available"

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

25  End If

26 End If

27End Sub

Similarly we can check email availability by writing following code in TextChanged Event of email textbox

01protected void txtEmail_TextChanged(object sender, EventArgs e)

02    {

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

04        {

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

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

07            SqlConnection con = new SqlConnection(strConnection);

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

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

10 

11            con.Open();

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

13            con.Close();

14 

15            if (result >= 1)

16            {

17                imgEmail.ImageUrl = "unavailable.png";

18                imgEmail.Visible = true;

19                lblEmail.Text = "Email already registered";

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

21            }

22            else

23            {

24                imgEmail.ImageUrl = "tick.png";

25                imgEmail.Visible = true;

26                lblEmail.Text = "Available";

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

28            }

29        }

30    }