For this create a table Users in sql server database with ID,Uname,emlAddress columns
and add some records in it.
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
<asp:ScriptManager ID="ScriptManager1" runat="server"/>
<asp:UpdatePanel ID="UpdatePanel1" runat="server">
<ContentTemplate>
UserName:
<asp:TextBox ID="txtUName" runat="server"
ontextchanged="txtUName_TextChanged"
AutoPostBack="True"/>
<asp:Image ID="imgUsr" runat="server" Visible="false"/>
<asp:Label ID="lblUsr" runat="server"/>
Email ID:
<asp:TextBox ID="txtId" runat="server"
AutoPostBack="True"
ontextchanged="txtId_TextChanged"/>
<asp:Image ID="imgId" runat="server" Visible="false"/>
<asp:Label ID="lblId" runat="server"></asp:Label>
</ContentTemplate>
</asp:UpdatePanel>
Write below mentioned code in TextChanged Event of textbox
C# CODE
protected void txtUName_TextChanged(object sender, EventArgs e)
{
if (txtUName.Text != string.Empty)
{
string strConnection = ConfigurationManager.ConnectionStrings
["ConnectionString"].ConnectionString;
string strSelect = "SELECT COUNT(*) FROM Users WHERE
Uname = @Username";
SqlConnection con = new SqlConnection(strConnection);
SqlCommand cmd = new SqlCommand(strSelect,con);
SqlParameter user = new SqlParameter("@Username", SqlDbType.VarChar);
user.Value = txtUName.Text.Trim().ToString();
cmd.Parameters.Add(user);
con.Open();
int result = (Int32)cmd.ExecuteScalar();
con.Close();
if (result >= 1)
{
imgUsr.ImageUrl = "unavailable.png";
imgUsr.Visible = true;
lblUsr.Text = "Username not available";
lblUsr.ForeColor = System.Drawing.Color.Red;
}
else
{
imgUsr.ImageUrl = "tick.png";
imgUsr.Visible = true;
lblUsr.Text = "Available";
lblUsr.ForeColor = System.Drawing.Color.Green;
}
}
}
Similarly we can check email availability by writing following code
protected void txtId_TextChanged(object sender, EventArgs e)
{
if (txtId.Text != string.Empty)
{
string strConnection = ConfigurationManager.ConnectionStrings
["ConnectionString"].ConnectionString;
string strSelect = "SELECT COUNT(*) FROM Users WHERE emlAddress = @Email";
SqlConnection con = new SqlConnection(strConnection);
SqlCommand cmd = new SqlCommand(strSelect, con);
cmd.Parameters.AddWithValue("@Email", txtId.Text.Trim().ToString());
con.Open();
int result = (Int32)cmd.ExecuteScalar();
con.Close();
if (result >= 1)
{
imgId.ImageUrl = "unavailable.png";
imgId.Visible = true;
lblId.Text = "Email already registered";
lblId.ForeColor = System.Drawing.Color.Red;
}
else
{
imgId.ImageUrl = "tick.png";
imgId.Visible = true;
lblId.Text = "Available";
lblId.ForeColor = System.Drawing.Color.Green;
}
}
}
