Beauty_Salon/BeautySalon/BeautySalonDBModels/Implements/SpecialisationDatabase.cs

using BeautySalonDBModels.Models;
using Npgsql;

namespace BeautySalonDBModels.Implements
{
    public class SpecialisationDatabase : AbstractWorkWithStorage<Specialisation>
    {
        public override void Add(Specialisation specialisation)
        {
            using var conn = GetConnection();
            conn.Open();
            using var cmd = new NpgsqlCommand("INSERT INTO specialisations (specialisation_id, specialisation_name) VALUES (nextval('seq_specialisation'), @Name)", conn);
            cmd.Parameters.AddWithValue("@Name", specialisation.Name);
            cmd.ExecuteNonQuery();
        }


        public override Specialisation? GetObject(int id)
        {
            using var conn = GetConnection();
            conn.Open();
            using var cmd = new NpgsqlCommand("SELECT * FROM specialisations WHERE specialisation_id = @id", conn);
            cmd.Parameters.AddWithValue("@id", id);
            using var reader = cmd.ExecuteReader();

            if (reader.Read())
            {
                return new Specialisation
                {
                    SpecialisationId = reader.GetInt32(0),
                    Name = reader.GetString(1)
                };
            }
            return null;
        }

        public override List<Specialisation> GetObjects()
        {
            var specialisations = new List<Specialisation>();
            using var conn = GetConnection();
            conn.Open();
            using var cmd = new NpgsqlCommand("SELECT * FROM specialisations order by specialisation_id", conn);
            using var reader = cmd.ExecuteReader();
            while (reader.Read())
            {
                specialisations.Add(new Specialisation
                {
                    SpecialisationId = reader.GetInt32(0),
                    Name = reader.GetString(1)
                });
            }
            return specialisations;
        }

        public override Specialisation? Remove(int id)
        {
            var specialisation = GetObject(id);
            if (specialisation != null)
            {
                using var conn = GetConnection();
                conn.Open();
                using var cmd = new NpgsqlCommand("delete from specialisations where specialisation_id = @SpecialisationId", conn);
                cmd.Parameters.AddWithValue("@SpecialisationId", id);
                cmd.ExecuteNonQuery();
            }
            return specialisation;
        }

        public override void Update(Specialisation specialisation)
        {
            using var conn = GetConnection();
            conn.Open();
            using var cmd = new NpgsqlCommand("UPDATE specialisations SET specialisation_name = @Name WHERE specialisation_id = @SpecialisationId", conn);
            cmd.Parameters.AddWithValue("@Name", specialisation.Name);
            cmd.Parameters.AddWithValue("@SpecialisationId", specialisation.SpecialisationId);
            cmd.ExecuteNonQuery();
        }
    }
}