Raspisanie/Zurnal/RemaDateBase/RemoutDateBase.cs

using System;
using Microsoft.EntityFrameworkCore;

public class RemoteDateBaseContext : DbContext
{
    public RemoteDateBaseContext() { }

    public DbSet<GroupDao> Group { get; set; }
    public DbSet<UserDao> User { get; set; }
    public DbSet<PresnceDao> Presence { get; set; }

    protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
    {
        optionsBuilder.UseNpgsql("Host=localhost;Port=5432;Username=postgres;Password=123;Database=postgres");
    }

    protected override void OnModelCreating(ModelBuilder modelBuilder)
    {
        modelBuilder.Entity<GroupDao>().HasKey(group => group.Id);
        modelBuilder.Entity<GroupDao>().Property(group => group.Id).ValueGeneratedOnAdd();
        
        modelBuilder.Entity<UserDao>().HasKey(user => user.Guid);
        modelBuilder.Entity<UserDao>().Property(user => user.Guid).ValueGeneratedOnAdd();
        
        modelBuilder.Entity<PresnceDao>().HasKey(presence => new
        {
            presence.UserGuid,
            presence.Date,
            presence.IsAttendensy,
            presence.LessonNumber
        });
    }
}