? vs ?? sql code example

Example: difference between nosql and sql

SQL						|    NoSQL
  relational			| non-relational
  						|
use structured query	| NoSQL databases have 
language and have a		| dynamic schemas for 
predefined schema.		| unstructured data.
						|
are vertically scalable | are horizontally scalable.
are table based			| are document, key-value,
						| graph or wide-column stores.
                        |
are better for multi-row| are better for unstructured 
transactions			| data like documents or JSON.