In Oracle PL/SQL, the term LEVEL refers to a pseudocolumn in
Oracle which is used in a hierarchical query to identify the
hierarchy level in numeric format. For each row returned by a
hierarchical query, the LEVEL pseudocolumn returns 1 for a root
row, 2 for a child of a root, and so on. In a tree-like
structure, the lowest level is the root (LEVEL=1) and it
progresses in unit incremental ratio. Note that LEVEL must be
used in the CONNECT_BY queries. The SELECT query below lists
employees reporting to a Manager: SELECT EMPNO, MGR_ID, LEVEL
FROM EMPLOYEES E START WITH MGR_ID = NULL CONNECT_BY PRIOR EMPNO
= MGR_ID; It can also be used as 'n' row generator using
recursive hierarchy. The query below generates 50 sequence
numbers. SELECT LEVEL SEQ CONNECT_BY LEVEL <= 50; Related Code
Snippets: