Add Database Connection to Installer file

Installers/DatabaseInstaller.cs

@@ -0,0 +1,17 @@
+using Diary.Data;
+using Microsoft.EntityFrameworkCore;
+
+namespace Diary.Installers
+{
+	public static class DatabaseInstaller
+	{
+		public static IServiceCollection AddDatabase(this IServiceCollection services, IConfigurationRoot config)
+		{
+			return services.AddDbContext<DiaryDBContext>(opt =>
+			{
+				string connectionString = config.GetConnectionString("Diary");
+				opt.UseSqlServer(connectionString);
+			});
+		}
+	}
+}