---
# System prepended metadata

title: Untitled

---

```ruby=

gsub vs gsub!


3.*2 + 1
# ==> 7

3.*(2 + 1)
# ==> 9

array.map(&:method_name) 
array.map {|a| a.method_name } 
:method_name.to_proc

includes Foo
extends Foo


find
find_by
where

each
find_each

includes
joins
- preload vs eager_load


HAVING
CURSOR
EXPLAIN
ANALYZE
SEQUENCE
VACUUM
CTE

```