面试题与答案

Oracle database is comprised of three types of files. One or more datafiles, two are more redo log files, and one or more control files.

There are tablespaces and database's schema objects.

A database is divided into Logical Storage Unit called tablespaces. A tablespace is used to grouped related logical structures together.

Every Oracle database contains a tablespace named SYSTEM, which is automatically created when the database is created. The SYSTEM tablespace always contains the data dictionary tables for the entire database.

Each databases logically divided into one or more tablespaces one or more data files are explicitly created for each tablespace.

A schema is collection of database objects of a user.

Schema objects are the logical structures that directly refer to the database's data. Schema objects include tables, views, sequences, synonyms, indexes, clusters, database triggers, procedures, functions packages and database links.

Yes

Yes

A table is the basic unit of data storage in an Oracle database. The tables of a database hold all of the user accessible data. Table data is stored in rows and columns.

A view is a virtual table. Every view has a query attached to it. (The query is a SELECT statement that identifies the columns and rows of the table(s) the view uses.)

A Partial Backup is any operating system backup short of a full backup, taken while the database is open or shut down.

A full backup is an operating system backup of all data files, on-line redo log files and control file that constitute ORACLE database and the parameter.

Yes

Yes

Yes

Views do not contain or store data.

UPDATE and DELETE Restrict - A referential integrity rule that disallows the update or deletion of referenced data. DELETE Cascade - When a referenced row is deleted all associated dependent rows are deleted.

There are two types of Synonyms Private and Public.

Each Index has an Index segment that stores all of its data.

Data Segment, Index Segment, Rollback Segment and Temporary Segment.

Clusters are groups of one or more tables physically stores together to share common columns and are often used together.

An integrity constraint is a declarative way to define a business rule for a column of a table.

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.

An Extent is a specific number of contiguous data blocks, obtained in a single allocation, and used to store a specific type of information.

A view is a virtual table. Every view has a Query attached to it. (The Query is a SELECT statement that identifies the columns and rows of the table(s) the view uses.)

A table is the basic unit of data storage in an ORACLE database. The tables of a database hold all of the user accessible data. Table data is stored in rows and columns.

- 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.