| dual [message #374180] |
Tue, 29 May 2001 12:50  |
theresia
Messages: 9
Registered: May 2001
|
Junior Member |
|
|
I used the syntax 'desc dual' in SQL PLUS and found that the dual table contains only one field named
as DUMMY and the type as varchar2(1).
And while issuing select * from dual the foll
output was seen
D
--
X
My doubt is how is it when the table is designed
in the above manner i am able to fetch a lot
of details from the dual table like
SELECT SYSDATE FROM DUAL, etc.
Could someone explain the above concept?
|
|
|
|
| Re: dual [message #374181 is a reply to message #374180] |
Tue, 29 May 2001 13:36  |
Jon
Messages: 483
Registered: May 2001
|
Senior Member |
|
|
DUAL is, as you found out, a single-row table. SELECTing SYSDATE from DUAL will therefore return one row, just as selecting SYSDATE from a five-row table would return five sysdates, and selecting 'X' from a five-thousand row table would return five-thousand X's. In other words, DUAL functions just like any other table as far as selecting SYSDATE goes.
Try the following:
select sysdate from dual where dummy = 'X';
select sysdate from dual where dummy = 'Y';
|
|
|
|
] 
Blog
Search
Help
Members
Register
Login
Home
