Answer:- Dual is a small oracle worktable,which consists of only 1 row and 1 column and contains the value x in that column.
- Besides arithmetic calculations,it also supports date retrieval and its formatting.
- For output of Arithmetic calculations (e.g. 2*2),to be output on SCREEN,SQL statement is SELECT.
- But,SELECT must have a table in its FROM clause,otherwise SELECT fails.
- To facilitate such calculations via SELECT,Oracle provides DUMMY TABLE called DUAL.
e.g. SELECT 2*2 FROM dual;