❔ SELECT MAX ID from textbox

private void txtNIDPROJETOS_TextChanged(object sender, EventArgs e)
        {
            string query = "select max(nensaio) from tbl_acoes where idProjetos = '" + txtNIDPROJETOS.Text + "'";
            SqlCommand cmd = new SqlCommand(query, con);
            con.Open();
            SqlDataReader reader = cmd.ExecuteReader();
            while (reader.Read())
            {
                txtEnsaioID.Text = reader["nensaio"].ToString();
            }
            con.Close();
        }

private void txtNIDPROJETOS_TextChanged(object sender, EventArgs e)
        {
            string query = "select max(nensaio) from tbl_acoes where idProjetos = '" + txtNIDPROJETOS.Text + "'";
            SqlCommand cmd = new SqlCommand(query, con);
            con.Open();
            SqlDataReader reader = cmd.ExecuteReader();
            while (reader.Read())
            {
                txtEnsaioID.Text = reader["nensaio"].ToString();
            }
            con.Close();
        }

var query = "select max(nensaio) from tbl_acoes where idProjetos = '" + txtNIDPROJETOS.Text + "'";
var cmd = new SqlCommand(query, con);
con.Open();
var result = cmd.ExecuteScalar();
con.Close();

var query = "select max(nensaio) from tbl_acoes where idProjetos = '" + txtNIDPROJETOS.Text + "'";
var cmd = new SqlCommand(query, con);
con.Open();
var result = cmd.ExecuteScalar();
con.Close();

select max(nensaio) from tbl_acoes where idProjetos = idProjetos;

select max(nensaio) from tbl_acoes where idProjetos = idProjetos;

'; DROP TABLE [dbo].[tbl_acoes]; --

'; DROP TABLE [dbo].[tbl_acoes]; --

private void InserirIDAcoes()
        {
            var query = "select max(nensaio) from tbl_acoes"; 
            var cmd = new SqlCommand(query, con);
            con.Open();
            var result = cmd.ExecuteScalar();
            con.Close();
        }

private void InserirIDAcoes()
        {
            var query = "select max(nensaio) from tbl_acoes"; 
            var cmd = new SqlCommand(query, con);
            con.Open();
            var result = cmd.ExecuteScalar();
            con.Close();
        }

private void InserirIDAcoes()
        {
            var query = "select max(nensaio) from tbl_acoes"; 
            var cmd = new SqlCommand(query, con);
            con.Open();
            var result = cmd.ExecuteScalar();
            con.Close();
        }

private void InserirIDAcoes()
        {
            var query = "select max(nensaio) from tbl_acoes"; 
            var cmd = new SqlCommand(query, con);
            con.Open();
            var result = cmd.ExecuteScalar();
            con.Close();
        }

ALTER TABLE Essays
ADD CONSTRAINT fk_essay_id
FOREIGN KEY (projectId)
REFERENCES Projects(id)

ALTER TABLE Essays
ADD CONSTRAINT fk_essay_id
FOREIGN KEY (projectId)
REFERENCES Projects(id)

ALTER TABLE Aactions
ADD CONSTRAINT fk_action_id
FOREIGN KEY (essayId)
REFERENCES Essays(id)

ALTER TABLE Aactions
ADD CONSTRAINT fk_action_id
FOREIGN KEY (essayId)
REFERENCES Essays(id)

public class Program
{
    public static void Main()
    {
        var conn = new SqlConnection("Data Source=.;Initial Catalog=Experiments;User Id=sa;Password=aaaAAA!!!");

        var query = "SELECT COUNT(*) FROM Actions;";

        using var cmd = new SqlCommand(query, conn);
        conn.Open();
        var result = cmd.ExecuteScalar();

        if (result != null)
        {
            Console.WriteLine($"Result was: {result}");
        }

        conn.Close();
    }
}

public class Program
{
    public static void Main()
    {
        var conn = new SqlConnection("Data Source=.;Initial Catalog=Experiments;User Id=sa;Password=aaaAAA!!!");

        var query = "SELECT COUNT(*) FROM Actions;";

        using var cmd = new SqlCommand(query, conn);
        conn.Open();
        var result = cmd.ExecuteScalar();

        if (result != null)
        {
            Console.WriteLine($"Result was: {result}");
        }

        conn.Close();
    }
}

var conn = new SqlConnection(@"Data Source=(LOCALDB)\\MSSQLLocalDB;Initial Catalog=ssms;Integrated Security=True");

var conn = new SqlConnection(@"Data Source=(LOCALDB)\\MSSQLLocalDB;Initial Catalog=ssms;Integrated Security=True");

SqlConnection con = new SqlConnection();
            con.ConnectionString = "Data Source";
            con.Open();
            string userid = txtUtilizador.Text;
            string password = txtSenha.Text;
            SqlCommand cmd = new SqlCommand("select utilizador,password from tbl_login where utilizador='" + txtUtilizador.Text + "'and password='" + txtSenha.Text + "'", con);
            SqlDataAdapter da = new SqlDataAdapter(cmd);
            DataTable dt = new DataTable();
            da.Fill(dt);
            if (dt.Rows.Count > 0)
            {
                this.Hide();
                MessageBox.Show("sucess!");
                MenuPrincipal sistema = new MenuPrincipal();
                sistema.ShowDialog();
            }
            else
            {
                MessageBox.Show("Utilizador or password invalid");
            }
            con.Close();

SqlConnection con = new SqlConnection();
            con.ConnectionString = "Data Source";
            con.Open();
            string userid = txtUtilizador.Text;
            string password = txtSenha.Text;
            SqlCommand cmd = new SqlCommand("select utilizador,password from tbl_login where utilizador='" + txtUtilizador.Text + "'and password='" + txtSenha.Text + "'", con);
            SqlDataAdapter da = new SqlDataAdapter(cmd);
            DataTable dt = new DataTable();
            da.Fill(dt);
            if (dt.Rows.Count > 0)
            {
                this.Hide();
                MessageBox.Show("sucess!");
                MenuPrincipal sistema = new MenuPrincipal();
                sistema.ShowDialog();
            }
            else
            {
                MessageBox.Show("Utilizador or password invalid");
            }
            con.Close();

public class UserService
{
    private readonly UserRepository _userRepository;
    private readonly AppSettings _settings;

    public UserService(UserRepository userRepository, AppSettings settings)
    {
        _userRepository = userRepository;
        _settings = settings;
    }

    public User? LoginUser(string username, string password)
    {
        var hash = BcryptHelper.Hash(password, _settings.UserPasswordSalt);

        var dbUser = _userRepository.GetUser(username, hash);

        if (dbUser == null)
        {
            return null;
        }
        return User.FromDbUser(dbUser);
    }
}

public class UserRepository
{
    private readonly SqlConnection _connection;

    public UserRepository(SqlConnection connection)
    {
        _connection = connection;
    }

    public DbUser? GetUser(string username, string passwordHash)
    {
        var param = new { Username = username, PasswordHash = passwordHash };
        var result = _connection.Query<DbUser>("SELECT Username FROM [Users] WHERE [Username] = @Username AND [PasswordHash] = @PasswordHash", param)?.ToList();

        return result?.SingleOrDefault();
    }
}

public class UserService
{
    private readonly UserRepository _userRepository;
    private readonly AppSettings _settings;

    public UserService(UserRepository userRepository, AppSettings settings)
    {
        _userRepository = userRepository;
        _settings = settings;
    }

    public User? LoginUser(string username, string password)
    {
        var hash = BcryptHelper.Hash(password, _settings.UserPasswordSalt);

        var dbUser = _userRepository.GetUser(username, hash);

        if (dbUser == null)
        {
            return null;
        }
        return User.FromDbUser(dbUser);
    }
}

public class UserRepository
{
    private readonly SqlConnection _connection;

    public UserRepository(SqlConnection connection)
    {
        _connection = connection;
    }

    public DbUser? GetUser(string username, string passwordHash)
    {
        var param = new { Username = username, PasswordHash = passwordHash };
        var result = _connection.Query<DbUser>("SELECT Username FROM [Users] WHERE [Username] = @Username AND [PasswordHash] = @PasswordHash", param)?.ToList();

        return result?.SingleOrDefault();
    }
}

using System.Data.SqlClient;
using Dapper;

using System.Data.SqlClient;
using Dapper;

var param = new { Username = username, PasswordHash = passwordHash };
        var result = _connection.Query<DbUser>("SELECT Username FROM [Users] WHERE [Username] = @Username AND [PasswordHash] = @PasswordHash", param)?.ToList();

var param = new { Username = username, PasswordHash = passwordHash };
        var result = _connection.Query<DbUser>("SELECT Username FROM [Users] WHERE [Username] = @Username AND [PasswordHash] = @PasswordHash", param)?.ToList();