Set - 7

Question 11 :

Deleting the Duplicate rows in the table

Answer :

We can delete the duplicate rows in the table by using the Rowid


Question 12 :

Can U disable database trigger? How?

Answer :

Yes. With respect to table
ALTER TABLE TABLE
[[ DISABLE all_trigger ]]


Question 13 :

What is pseudo columns ? Name them?

Answer :

A pseudocolumn behaves like a table column, but is not actually stored in the table. You can select from pseudocolumns, but you cannot insert, update, or delete their values. This section describes these pseudocolumns:
* CURRVAL
* NEXTVAL
* LEVEL
* ROWID
* ROWNUM


Question 14 :

How many columns can table have?

Answer :

The number of columns in a table can range from 1 to 254.
Is space acquired in blocks or extents ?
In extents .


Question 15 :

What is clustered index?

Answer :

In an indexed cluster, rows are stored together based on their cluster key values . Can not applied for HASH.