First commit that builds.

code/MessengerBroker.Db/BrokerDbContext.cs

@@ -0,0 +1,32 @@
+using MessengerBroker.Db.Model;
+using Microsoft.EntityFrameworkCore;
+
+namespace MessengerBroker.Db
+{
+    public class BrokerDbContext : DbContext
+    {
+        private string connectionString;
+
+        public DbSet<Sync> Syncs { get; }
+
+        public DbSet<User> Users { get; }
+
+        public DbSet<Message> Messages { get; }
+
+        public BrokerDbContext(string connectionString)
+        {
+            this.connectionString = connectionString;
+        }
+
+        protected override void OnModelCreating(ModelBuilder modelBuilder)
+        {
+            base.OnModelCreating(modelBuilder);
+        }
+
+        protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
+        {
+            base.OnConfiguring(optionsBuilder);
+            optionsBuilder.UseSqlServer(this.connectionString);
+        }
+    }
+}