SQL - What is Dual table?

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What is Dual table?

what is dual table which is used as a table in sql...

Total Answers and Comments: 5

Last Update: October 08, 2008 Asked by: kumaranvp

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Submitted by: sat_orcl

Dual table is dummy table and it is having only one column with varchar2 datatype

Above answer was rated as good by the following members:
bikash_tamang, JohanQS

July 24, 2008 02:08:23

svsraju81

Member Since: July 2008 Contribution: 1

RE: What is Dual table?

Dual table is a temporary table it contains a single row and single column. If we return a data from dual table it gives a single row.

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August 10, 2008 01:42:22

nikhilsaxena

Member Since: February 2008 Contribution: 3

RE: What is Dual table?

It has single row and single column.

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August 29, 2008 06:46:29

sat_orcl

Member Since: August 2008 Contribution: 2

RE: What is Dual table?

Dual table is dummy table and it is having only one column with varchar2 datatype

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September 24, 2008 05:50:00

me.ranjeet

Member Since: September 2008 Contribution: 3

RE: What is Dual table?

dual is a table which is created by oracle along with the data dictionary. It consists of exactly one column whose name is dummy and one record. The value of that record is X. rene@ora92> desc dual Name Null? Type ----------------------- -------- ---------------- DUMMY VARCHAR2(1)rene@ora92> select * from dual;D-XThe owner of dual is SYS but dual can be accessed by every user. As dual contains exactly one row (unless someone fiddled with it) it is guaranteed to return exactly one row in select statements. Therefor dual is the prefered table to select a pseudo column (such as sysdate select sysdate from dualAlthough it is possible to delete the one record or insert additional records one really should not do that!.

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October 08, 2008 13:16:36

malapati

Member Since: October 2008 Contribution: 13

RE: What is Dual table?

Every database contains only one dual table that is also called as dummy table

dual is used to evaluate expressions

example:select 3+4+6 from dual; or select sysdate from dual

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