# DUAL table
# The following example returns the current operating system date and time
select sysdate from dual
# The following example generates numbers between start_value and end_value
select :start_value + level -1 n from dual connect by level <= :end_value - :start_value + 1
DUAL table has one column
DUMMY, defined to be
VARCHAR2(1) and only one row with a value
DUAL table is automatically created in
SYS schema when database is created. You can access it from any schema.
You can not change
You can use
DUAL table to call any function from SQL statement. It is useful because it has only one row and oracle optimizer knows everything about it.