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ORACLE Interview Questions and Answers
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31. Can a view based on another view?
Yes.
32. What are the advantages of views?
- Provide an additional level of table security, by restricting access to a predetermined set of rows and columns of a table.
- Hide data complexity.
- Simplify commands for the user.
- Present the data in a different perspective from that of the base table.
- Store complex queries.
33. What is an Oracle sequence?
A sequence generates a serial list of unique numbers for numerical columns of a database's tables.
34. What is a synonym?
A synonym is an alias for a table, view, sequence or program unit.
35. What are the types of synonyms?
There are two types of synonyms private and public.
36. What is a private synonym?
Only its owner can access a private synonym.
37. What is a public synonym?
Any database user can access a public synonym.
38. What are synonyms used for?
- Mask the real name and owner of an object.
- Provide public access to an object
- Provide location transparency for tables, views or program units of a remote database.
- Simplify the SQL statements for database users.
39. What is an Oracle index?
An index is an optional structure associated with a table to have direct access to rows, which can be created to increase the performance of data retrieval. Index can be created on one or more columns of a table.
40. How are the index updates?
Indexes are automatically maintained and used by Oracle. Changes to table data are automatically incorporated into all relevant indexes.
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