Added comments for EF core layer.

templates/mvc/src/MyCompanyName.MyProjectName.EntityFrameworkCore.DbMigrations/EntityFrameworkCore/MyProjectNameMigrationsDbContext.cs

@@ -11,6 +11,11 @@ using Volo.Abp.TenantManagement.EntityFrameworkCore;
 
 namespace MyCompanyName.MyProjectName.EntityFrameworkCore
 {
+    /* This DbContext is only used for database migrations.
+     * It is not used on runtime. See MyProjectNameDbContext for the runtime DbContext.
+     * It is a unified model that includes configuration for
+     * all used modules and your application.
+     */
     public class MyProjectNameMigrationsDbContext : AbpDbContext<MyProjectNameMigrationsDbContext>
     {
         public MyProjectNameMigrationsDbContext(DbContextOptions<MyProjectNameMigrationsDbContext> options) 

templates/mvc/src/MyCompanyName.MyProjectName.EntityFrameworkCore.DbMigrations/EntityFrameworkCore/MyProjectNameMigrationsDbContextFactory.cs

@@ -5,6 +5,8 @@ using Microsoft.Extensions.Configuration;
 
 namespace MyCompanyName.MyProjectName.EntityFrameworkCore
 {
+    /* This class is needed for EF Core console commands
+     * (like Add-Migration and Update-Database commands) */
     public class MyProjectNameMigrationsDbContextFactory : IDesignTimeDbContextFactory<MyProjectNameMigrationsDbContext>
     {
         public MyProjectNameMigrationsDbContext CreateDbContext(string[] args)

templates/mvc/src/MyCompanyName.MyProjectName.EntityFrameworkCore/EntityFrameworkCore/MyProjectNameDbContext.cs

@@ -7,11 +7,24 @@ using Volo.Abp.Users.EntityFrameworkCore;
 
 namespace MyCompanyName.MyProjectName.EntityFrameworkCore
 {
+    /* This is your actual DbContext used on runtime.
+     * It includes only your entities.
+     * It does not include entities of the used modules, because each module has already
+     * its own DbContext class. If you want to share some database tables with the used modules,
+     * just create a structure like done for AppUser.
+     *
+     * Don't use this DbContext for database migrations since it does not contain tables of the
+     * used modules (as explained above). See MyProjectNameMigrationsDbContext for migrations.
+     */
     [ConnectionStringName("Default")]
     public class MyProjectNameDbContext : AbpDbContext<MyProjectNameDbContext>
     {
         public DbSet<AppUser> Users { get; set; }
 
+        /* Add DbSet properties for your Aggregate Roots / Entities here.
+         * Also map them inside MyProjectNameDbContextModelCreatingExtensions.ConfigureMyProjectName
+         */
+
         public MyProjectNameDbContext(DbContextOptions<MyProjectNameDbContext> options)
             : base(options)
         {

templates/mvc/src/MyCompanyName.MyProjectName.EntityFrameworkCore/EntityFrameworkCore/MyProjectNameEntityFrameworkCoreModule.cs

@@ -30,13 +30,14 @@ namespace MyCompanyName.MyProjectName.EntityFrameworkCore
             context.Services.AddAbpDbContext<MyProjectNameDbContext>(options =>
             {
                 /* Remove "includeAllEntities: true" to create
-                 * default repositories only for aggregate roots
-                 */
+                 * default repositories only for aggregate roots */
                 options.AddDefaultRepositories(includeAllEntities: true);
             });
 
             Configure<AbpDbContextOptions>(options =>
             {
+                /* The main point to change your DBMS.
+                 * See also MyProjectNameMigrationsDbContextFactory for EF Core tooling. */
                 options.UseSqlServer();
             });
         }