DUAL Table in Oracle
It’s a DUMMY table.
It is not a “SQL” thing, nor is it necessarily a “function” thing, but it’s an “Oracle” thing.
The DUAL table is present in every Oracle database.
This special table contains just one column.
The column is named DUMMY, and it has a data type of VARCHAR2(1).
The DUAL table contains only one row. That row has a value in DUMMY of ‘X’.
The purpose of DUAL is simple — to have something to run a SELECT statement against when you don’t wish to retrieve any data in particular but instead simply wish to run a SELECT statement to get some other task accomplished.
For example, there’s an Oracle SQL function called SYSDATE that displays the current date according to the operating system of the server on which the Oracle database is installed.
If you wish to get the value of SYSDATE without wading through a bunch of table data from your application, you can simply execute the following SQL statement:
