Date value returns random integer - oracle - sql

Question

select 31/10/2016 as date from dual;
Retuns me a long integer value.
Whereas,
select '31/10/2016' as date from dual;
Gives me the required result.
What is the transformation happening when we give the date value without quotes?

Answer 1

Non of them are right.
The 1st is an arithmetic computation.
31/10/2016 = ((31 / 10) / 2016) = 3.1 / 2016 = 0.00153...
The 2nd is a string
select '31/10/2016' + 1 from dual;
ORA-01722: invalid number
ANSI/ISO Dates literals are written as
DATE 'YYYY-MM-DD'
Datetime Literals
In your case
DATE '2016-10-31'
select DATE '2016-10-31' + 1 from dual;
2016-11-01 00:00:00
P.s.
date is a reserved word.
You couldn't have used it as an alias for your columns without getting a parsing error.
B Oracle Reserved Words, Keywords, and Namespaces

Answer 2

select 31/10/2016 : Its arithmetic operations ( dividation )
select '31/10/2016' : Using quotes its become string. Single quotes delimit a string constant or a date/time constant.

Answer 3

When you execute
select 31/10/2016 as date from dual;
Oracle interprets it as a airthmatic division operation and divides 31 by 10 and result by again 2016 .
When you execute
select '31/10/2016' as date from dual;
Oracle interprets as it as a string and it will throw error since Date is a reserved keyword and you cannot use reserve keywords either as column names or as alias.
The right way to do it as below:
select to_date('31/10/2016','dd/mm/yyyy') as dte from dual;