Add features, limitations and relations sections to README

README.md

@@ -7,6 +7,7 @@ QuerySets for golang (go): typesafe, codegenerated ORM with GORM under the hood
 * [Installation](#installation)
 * [Usage](#usage)
   * [Define models](#define-models)
+  * [Relation with GORM](#relation-with-gorm)
   * [Create models](#create)
   * [Select models](#select)
   * [Update models](#update)
@@ -18,6 +19,9 @@ QuerySets for golang (go): typesafe, codegenerated ORM with GORM under the hood
   * [Why not any ORM?](#why-not-any-orm)
   * [Why not raw SQL queries?](#why-not-raw-sql-queries)
   * [Why not go-kallax?](#why-not-go-kallax)
+* [How it relates to another languages ORMs](#how-it-relates-to-another-languages-orms)
+* [Features](#features)
+* [Limitations](#limitations)
 
 
 # Installation
@@ -88,6 +92,28 @@ See full autogenerated file [here](https://github.com/jirfag/go-queryset/blob/ma
 
 Now you can use this queryset for creating/reading/updating/deleting. Let's take a lot at these operations.
 
+## Relation with GORM
+You can not embed `gorm.Model` into your model (e.g. if you don't need `DeletedAt` field), but you must use `*gorm.DB`
+to properly work. Don't worry if you don't use GORM yet, it's [easy to create `*gorm.DB`](http://jinzhu.me/gorm/database.html#connecting-to-a-database):
+```go
+import (
+    "github.com/jinzhu/gorm"
+    _ "github.com/jinzhu/gorm/dialects/mysql"
+)
+
+func getGormDB() *gorm.DB {
+	db, err := gorm.Open("mysql", "user:password@/dbname?charset=utf8&parseTime=True&loc=Local")
+	// ...
+}
+```
+
+If you already use another ORM or raw `sql.DB`, you can reuse your `sql.DB` object (to reuse connections pool):
+```go
+	var sqlDB *sql.DB = getSQLDBFromAnotherORM()
+	var gormDB *gorm.DB
+	gormDB, err = gorm.Open("mysql", sqlDB)
+```
+
 ## Create
 ```go
 u := User{
@@ -370,3 +396,18 @@ No type-safety, a lot of boilerplate code.
 ## Why not [go-kallax](https://github.com/src-d/go-kallax)?
 1. It works only with PostgreSQL. Go-queryset supports mysql, postgresql, sqlite, mssql etc (all that gorm supports).
 2. Lacks simplier model updating interface
+
+## How it relates to another languages ORMs
+QuerySet pattern is similar to:
+* [Django QuerySet](https://docs.djangoproject.com/en/dev/ref/models/querysets/), but better than it because of type-safety (Python)
+* [Rails Active Record and it's scopes](http://guides.rubyonrails.org/active_record_querying.html#scopes), but better than it because of type-safety (Ruby)
+
+# Features
+* 100% typesafe: there is no one method with `interface{}` arguments.
+* QuerySet pattern allows to reuse queries by defining [custom methods](https://github.com/jirfag/go-queryset/blob/master/examples/comparison/gorm4/gorm4.go#L30) on it.
+* Supports all DBMS that GORM supports: MySQL, PostgreSQL, Sqlite3, SQL Server.
+* Supports creating, selecting, updating, deleting of objects.
+
+# Limitations
+* Joins aren't supported
+* Struct tags aren't supported