SQL DUAL Table Usage Guide

In SQL, the dual table is a virtual table used primarily for querying when an actual table is not available. In Oracle databases, the dual table is a system-provided virtual table containing only one row with one column of data. It is often used for functions, calculating expressions, or returning fixed values.

For example, the dual table can be used to execute some simple query operations.

SELECT SYSDATE FROM dual;

The above query will return the current date and time. In this case, the dual table doesn’t actually contain any real data, it is just a placeholder used to perform queries.