private void button1_Click(object sender, EventArgs e) { Connection conn = new Connection(); DataTable dt = new DataTable(); MySqlDataAdapter adapter = new MySqlDataAdapter(); MySqlCommand command = new MySqlCommand(); String QuesLog = "SELECT * FROM `uzytkownicy` WHERE `LOGIN` = @usn AND `HASLO` = @pass"; command.CommandText = QuesLog; command.Connection = conn.GetConnection(); command.Parameters.Add("@usn", MySqlDbType.VarChar).Value = textBox1.Text; command.Parameters.Add("@pass", MySqlDbType.VarChar).Value = textBox2.Text; adapter.SelectCommand = command; try { adapter.Fill(dt); if (dt.Rows.Count > 0) { DataRow row = dt.Rows[0]; Id_kli = row["ID_UZYT"].ToString(); this.Hide(); if (textBox1.Text.Equals("admin")) { admin ad = new admin(); this.Hide(); ad.Show(); } else { Client cl = new Client(); this.Hide(); cl.Show(); } } else { if (textBox1.Text.Trim().Equals("") && !textBox2.Text.Trim().Equals("")) { MessageBox.Show("Give your login!", "Empty login", MessageBoxButtons.OK, MessageBoxIcon.Error); textBox2.Text = textBox1.Text = ""; } else if (textBox2.Text.Trim().Equals("") && !textBox1.Text.Trim().Equals("")) { MessageBox.Show("Give your password!", "Empty password", MessageBoxButtons.OK, MessageBoxIcon.Error); textBox2.Text = textBox1.Text = ""; } else if (textBox1.Text.Trim().Equals("") && textBox2.Text.Trim().Equals("")) { MessageBox.Show("Give your password and login!", "Empty login and password", MessageBoxButtons.OK, MessageBoxIcon.Error); textBox2.Text = textBox1.Text = ""; } else { MessageBox.Show("Wrong username or password!", "ERROR", MessageBoxButtons.OK, MessageBoxIcon.Error); textBox2.Text = textBox1.Text = ""; } } } catch { MessageBox.Show("Unable to connect with database!", "ERROR", MessageBoxButtons.OK, MessageBoxIcon.Error); } }