what does order 1,2 do

Question

Imagine we have following table

create table t
  (item number,
   bin number,
   primary key (bin , item) );

I have used insert into command to insert several values into table t, now i am interested in what does this code

select * from t
  order by 1,2;

As far as i know it selects everything from table t and sorts it, because order means to sort selected query using condition listed in order command, but order 1,2 i could not understand what does it means, could you help me ?

Answer 1

It sorts the result by the first and second column, so in your case it's identical to

select *
from t
order by item, bin;

Answer 2

select * from t
  order by item, bin; // just different written but result is same.

Result will be sorted by first and second column.

Difference is in readability of code so if someone don't know information about table, your select says nothing him. Person only knows that result will be sorted by 1. and 2. column, nothing more.