DUAL table is a dummy table which
contains one row and one column and
by default it is present in
database.It contains a single
VARCHAR2(1) column known as DUMMY
with a value "X".
It can be accessed by all users but
the owner of DUAL table is SYS. We
can use this table to perform some
calculation and we can also display
system date.
It is used when we are interested in
result only.
We can see the structure of the DUAL table using the following query:
DESC DUAL;
Output will be like this:
Name Null? Type
--------------------------- ------
DUMMY VARCHAR2(1)
We can see the data of dual table using the following query:
SELECT * FROM DUAL;
Output will be like this:
DUMMY
----------
X
Query to check the system date using dual table:
SELECT sysdate FROM DUAL ;
Output will be like this:
SYSDATE
---------
25-JAN-16
Query to perform some calculation using dual table:
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