Database Management System

HTML files are not context dependent and by default, these are linked to browser.

 Distribution is dividing the data fields to their respectives, but query processing does not allow any kind of distribution. Query processing allows optimizing, evaluation and parsing and translation.

Rollback is used to recover from transaction failure. We make savepoints, like checkpoints to save our transactions.

5NF is known as projection join normal form (PJ/NF) if R relation is join dependency.

Relation is same as in BCNF but additionally, it has more than one multivalued dependencies.

 For every functional dependency, X->Y in a set F of functional dependencies are over. Unfortunately, BCNF is not dependency preserving. Dependency preserving is not a condition for BCNF decomposition.

 A transaction can never be partially aborted or partially commited or partially terminated.

It is not compulsary for SQL expression to return a value.

Foreign key stores the primary key of others tables and is used for relationship.

The ANSI/SPARC is a three level architecture. This shows that a data model can be an external model (or view), a conceptual model, or a physical model. This is not the only way to look at data models, but it is an useful way, particularly when comparing models.

 GRANT and REVOKE control the privileges over the different objects.

 Candidate Key is the only system guranteed way of pin pointing some specific tuple by some candidate key value.

 A data type as used in a typical relational database might be the set of integers. The popularity of the network data model coincided with the popularity of the hierarchical data model.Thus, the Network model uses SET .

To SAVE and EXIT from the transaction, we should write COMMIT, or if we have made savepoint, then we have revert back then, make SAVEPOINT. So,  we can make either COMMIT or SAVEPOINT according to the query.

Candidate keys are special subsets of superkeys that do not have any extraneous information in them. Each table may have one or more candidate keys. A superkey is a combination of attributes that can be uniquely used to identify a database record. A table might have many superkeys. Hence, both the options 1 and 2 are correct.

 Data aggregation is when the data is accrued, possibly from various sources.

View is like a window to the table in the database or of the database, through which we can see the database. VIEW is a command to make a view of some essential attributes or columns of a database or table, so it is also called a sub-schema.

This is false. View has no independent existence. It is a virtual table.

(A Primary Key or part of it can not be null) - the rule says that 'null' is a special value in a relational database and it does not mean blank or zero.

Versioning involves recording and managing changes to a multi-user GEO database by creating a 'version' of the database—an alternative, independent, persistent view of the database that does not involve in creating a copy of the data and supports multiple concurrent.

 A superkey is a combination of attributes that can be uniquely used to identify a database record. A table might have many superkeys.

The cartesian product of two tables combines each row in one table with each row in the other table.

System failures are detected by transaction manager. They also maintain the state of the base prior to failure.

Fast access is the main advantage of the hash file by indexing concept and it searches through the indexes.

X associated to any number of Y but Y is associated with only one entity of X , so relationship is one to many.

Insert is used to insert a new row in a table - like insert in to table values (data1 , XYZ ) ; and length of the list is directly proportional to the insertion made.