Dual Table
Dual Table:
- Oracle database provided a default table called dual table.
- Dual Table is dummy table mainly it is used for execution purpose.
- Dual Table has one column and one row dual is also called as an dummy table because it has a dual name called dummy.
- Dual is not related to table we cannot fetch from table.
Query : SELECT * form dual;
Query : SELECT 1+1 form dual;
Output : the above query shows result of 2.
Query : SELECT 1+1 form emp;
Output : the above query shows result of 2 with 14 rows because emp table contain 14 rows.
Query : SELECT ename form dual;
Output : Error invalid identifier.