Hi

Dual is a virtual table ...it do not eists .

It is used to query fro pseudo columns..

eg;

select sysdate from dual

Dummy table with one row and one column we can select from it but cant insert update delete.

Hello Friends

Dual is a dummy table which has one row and one column .

DUAL IS A DUMMY TABLE. WE CAN INSERT UPDATE AND DELETE FROM DUAL TABLE IF YOU LOG IN WITH SYSTEM/MANGER PRIVILLAGES.

EXAMPLE:

SELECT * FROM DUAL;
no rows selected


DESC DUAL
Name Null? Type
----------------------------------------- -------- ----------------------------
DUMMY VARCHAR2(1)


SQL> INSERT INTO DUAL VALUES('Y');

1 row created.


SQL> SELECT * FROM DUAL;

D
-
Y


SQL> UPDATE DUAL SET DUMMY 'S';

1 row updated.

SQL> SELECT * FROM DUAL;

D
-
S


SQL> DELETE FROM DUAL;

1 row deleted.

SQL> SELECT * FROM DUAL;

no rows selected


EVEN IF U INSERT A ROW INTO DUAL TABLE STILL IT CAN BE USED TO RETRIEVE DATA FOR PSUEDO COLUMNS.

YOU CAN INSERT ONLY ONE RECORD INTO THE DUAL TABLE IF U TRY TO INSERT ANOTHER RECORD IT WILL NOT GIVE ANY ERROR IT WILL JUST DISPLAY 1 ROW INSERTED BUT U WILL FIND ONLY 1 ROW. ie THE PREVIOUS RECORD.


REGARDS
SHARAT