Get Hierarchial data in the table in Oracle

There is a construct called by name Connect By to get the hierarchial data (Parent child relationship data) inside the table in oracle

The CONNECT BY clause specifies the relationship between parent rows and child rows of the hierarchy. The connect_by_condition can be any condition, however, it must use the PRIOR operator to refer to the parent row.

Ex:

SELECT firstname, lastname, empid, managerid, LEVEL
   FROM emp
   CONNECT BY PRIOR empid = managerid;