Database

Question

I am designing a login form in windows application , how can I compare whether the details enter by user is available in Data base or not

Shankar M · Answer

Hi Gagan , Validating the User Name and Password against the Database is quite simple only. Try this Create a VALIDATEUSER Table in your SQL Server Database. CREATE TABLE VALIDATEUSER(USERNAME VARCHAR(20), PASSWORD VARCHAR(20), STATUS INT); Sample Insert Statement : INSERT INTO VALIDATEUSER VALUES('Ravi','ravi123',1) Try this Code, private void btn_validate_Click(object sender, EventArgs e) { if (string.IsNullOrEmpty(txt_username.Text)) { MessageBox.Show("Please Enter the User Name"); } else if (string.IsNullOrEmpty(txt_password.Text)) { MessageBox.Show("Please Enter Password"); } else { try { SqlConnection conn = new SqlConnection(); conn.ConnectionString = @"Data Source = ServerName;Initial Catalog =DatabaseName; User id =UserName; Password = password;"; SqlCommand cmd = new SqlCommand("SELECT USERNAME,PASSWORD FROM VALIDATEUSER WHERE USERNAME =@USRNAME AND PASSWORD = @PWD",conn); cmd.Parameters.AddWithValue("@USRNAME", txt_username.Text); cmd.Parameters.AddWithValue("@PWD", txt_password.Text); cmd.Connection = conn; conn.Open(); DataTable dt = new DataTable(); SqlDataReader reader = cmd.ExecuteReader(CommandBehavior.CloseConnection); dt.Load(reader); if (dt.Rows.Count == 0) { MessageBox.Show("Invalid User Name /Password"); } else { MessageBox.Show("User Name is Valid"); } cmd.Dispose(); conn.Dispose(); } catch (Exception ex) { MessageBox.Show(ex.Message); } } } Here, We create an instance of SqlConnection Class and SqlCommand Class. The SqlCommand uses the SqlConnection object to execute the SQL Statement. Using the AddWithValue Method we pass the Parameter and the value that is UserName and Password. Then, I have loaded the result set in to DataTable object.You can do it any of many ways. Then, if the count of the DataTable is 0 Indicates that no records are returned so the User Name of Password entered is Invalid.

Sathish Pabbathi · Answer

Hi Check this Link... http://www.dotnetfunda.com/forums/thread9061-how-to-read-values-from-database-for-loginpagewindows-forms.aspx

Satyapriya Nayak · Answer

using System; using System.Collections.Generic; using System.ComponentModel; using System.Data; using System.Drawing; using System.Linq; using System.Text; using System.Windows.Forms; using System.Data.OleDb; namespace Registration_in_Msaccess { public partial class Form1 : Form { string ConnectionString = System.Configuration.ConfigurationSettings.AppSettings["dsn"]; OleDbCommand com; string str; public Form1() { InitializeComponent(); } private void btn_insert_Click(object sender, EventArgs e) { if (txtUserName.Text == "" || txtUserAddress.Text == "") { MessageBox.Show("Please insert the values"); } else { namecheck(); } } private void namecheck() { OleDbConnection con = new OleDbConnection(ConnectionString); con.Open(); str = "select count(*)from employee where ename='" + txtUserName.Text + "'"; com = new OleDbCommand(str, con); int count = Convert.ToInt32(com.ExecuteScalar().ToString()); con.Close(); if (count > 0) { lblMessage.Text = "Sorry! you can't take this username"; } else { lblMessage.Text = "You can take this username"; con.Open(); str = "insert into employee(ename,eaddress) values('" + txtUserName.Text + "','" + txtUserAddress.Text + "')"; com = new OleDbCommand(str, con); com.ExecuteNonQuery(); con.Close(); } } } }

Neha Sharma · Answer

Hi.. You can use the same code like web applications.

Database

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