Add project files.

DatamodelLibrary/StockContext.cs

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+using DataDomain;
+using Microsoft.EntityFrameworkCore;
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace DatamodelLibrary
+{
+    public class StockContext : DbContext
+    {
+        public DbSet<StockMember> Stocks { get; set; }
+        public DbSet<Person> Persons { get; set; }
+        public DbSet<Address> Addresses { get; set; }
+        public DbSet<PersonStock> PersonStocks { get; set; }
+        public DbSet<BackupRegister> BackupRegings { get; set; }
+
+        protected override void OnConfiguring(DbContextOptionsBuilder options)
+            => options.UseSqlite("Data Source=Stocks.db");
+    }
+}