Can you take online backup of a Control File If yes, How?

venu

• Sep 1st, 2012

Code
SQL> ALTER DATABASE backup controlfile TO trace AS <PATH> 

Specify the path where you want to store the controlfile backup.

neha.awasthi1

 Profile Answers by neha.awasthi1 Questions by neha.awasthi1

• May 18th, 2011

We can do this by suding RMAN:configure control file auto backup on;

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Answered by: MANAS KUMAR ROUT ( USA ) (TCS) (Eli LILLY ) - PFIZ

• Jul 6th, 2007

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Hey Ramesh,

I understand your interviewer's enthusiasm to know about the Foreign Key.? See foreign key definitions says its states the relationship of one attribute(Column) of one table to the corresponding column on the other table.

So one os a parent and other is child. PARENT is that table which holds the primary key and CHILD is table which holds the referential key. Hence every entry in the PRIMARY table is unique where as same entry might be repeating in the child table. BUT that same has to be present in the PARENT table (Primary KEY).

Now Going by definition Foreign key can be of two types :
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1.? ON DELETE SET NULL
2.? ON DELETE SET CASCADE

DETAILS:
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On delete set null :
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When a foreign key is created by on delete set null definition then when you delete one row from the primary?column (of parent table ) , then the corresponding entry in the foreign key table (Child table ) have the value "NULL" for that particular column.


ON Delete Set Cascade:
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When the foreign key is created by this definition then when you delete the primary column (any one row -unique data) , then the Child table forcefully deletes all the rows in the child table having same value for that particular column.


I hope u got the crux of the Foreign key
Thanks
Manas Kumar Rout
SAS Consultant
Oracle Certified Associate
Unix Consultant

shweta dhumal

• Sep 8th, 2011

foreign key is primary key of other table. for example: 'STUDENT' is one table which stores information about students and 'SID' is primary key in that table and 'MARKS' is another table which stor...

shweta dhumal

• Sep 8th, 2011

The purpose of the foreign key is to ensure referential integrity of the data. In other words, only values that are supposed to appear in the database are permitted. For example, say we have two tab...

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