/* This is a simple query which can generate a sequence of numbers. The following example generates a sequence of numbers from 1..100 */

select level from dual connect by level <= 100;

/*The above query is useful in various scenarios like generating a sequence of dates from a given date. The following query generates 10 consecutive dates */

select to_date('01-01-2017','mm-dd-yyyy')+level-1 as  dates from dual connect by level <= 10;

01-JAN-17
02-JAN-17
03-JAN-17
04-JAN-17
05-JAN-17
06-JAN-17
07-JAN-17
08-JAN-17
09-JAN-17
10-JAN-17

Remarks

level clause is responsible for generating N number of dummy records based on some specific condition.