What is Dual table?

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

Questions by kumaranvp   answers by kumaranvp

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  • Member Since Jul-2008 | Jul 24th, 2008

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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  • Sep 24th, 2008

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!.


  • Oct 8th, 2008

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


  • Sep 5th, 2010

Dual table is owned by SYS. Data dictionary come under SYS, dual is part of data dictionary. Dual table consist only one row and only one column containing value x

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sudipta kumar dhal

  • Sep 5th, 2011

Dual table is called a dummy table because it is not meant for storing any useful data.

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