Database Concepts Quiz

In an E-R diagram that uses Chen Notation attributes are represented by

• rectangle.

• square.

• ellipse.

• triangle.

Answer explanation

In Chen Notation for E-R diagrams, attributes are represented by ellipses. This distinguishes them from entities, which are shown as rectangles, and relationships, which are depicted as diamonds.

A logical schema,

• is a model usually a diagram with data structures expressed which are independent of DBMS.

• is a standard way of organizing information into accessible parts.

• describes how data is actually stored on disk.

• both (A) and (C)

Answer explanation

A logical schema is indeed a model that represents data structures independently of any specific Database Management System (DBMS), making the first choice correct. It does not describe physical storage, which is covered by a physical schema.

Related fields in a database are grouped to form a

• data file.

• data record.

• menu.

• bank.

Answer explanation

Related fields in a database are grouped together to form a data record, which represents a single entry in a database table. This is the correct choice, as it accurately describes the organization of data.

In an E-R diagram the uses Crows Foot Notation an entity set is represent by a

• rectangle.

• ellipse.

• diamond box.

• circle.

Answer explanation

In Crows Foot Notation, an entity set is represented by a rectangle. This visual representation helps distinguish entities from other components like attributes and relationships, which use different shapes.

The property / properties of a database system is / are :

• It is an integrated collection of logically related records.

• It consolidates separate files into a common pool of data records.

• Data stored in a database is independent of the application programs using it.

• All of the above.

Answer explanation

All the options describe key properties of a database system: it integrates related records, consolidates files into a common data pool, and ensures data independence from application programs. Thus, the correct answer is 'All of the above.'

The DBMS language component which can be embedded in a program is

• The data definition language (DDL).

• The data manipulation language (DML).

• The database administrator (DBA).

• A query language.

Answer explanation

The data manipulation language (DML) is designed for embedding in programs, allowing for operations like querying and updating data. In contrast, DDL is used for defining database structures, and DBA refers to a role, not a language.

The statement in SQL which allows to change the definition of a table is

• Alter.

• Update.

• Create.

• Select.

Answer explanation

The correct choice is 'Alter' because it is the SQL statement used to modify the structure of an existing table, such as adding or removing columns. 'Update' is for changing data, while 'Create' and 'Select' serve different purposes.

The Chen Notation ER model uses this symbol to represent weak entity set?

• Dotted rectangle.

• Diamond

• Doubly outlined rectangle

• None of these

Answer explanation

In the Chen Notation ER model, a weak entity set is represented by a doubly outlined rectangle. This distinguishes it from regular entities, which are shown with a single outline.

Which of the following operation is used if we are interested in only certain columns of a table?

• PROJECTION

• SELECTION

• UNION

• JOIN

Answer explanation

PROJECTION is the operation used to select specific columns from a table, allowing us to focus on only the data we need. In contrast, SELECTION filters rows, UNION combines tables, and JOIN merges tables based on related columns.

The RDBMS terminology for a row is

• tuple.

• relation.

• attribute.

• degree.

Answer explanation

In RDBMS terminology, a row is referred to as a 'tuple'. This term is used to describe a single record in a table, while 'relation' refers to the table itself, 'attribute' to the columns, and 'degree' to the number of attributes.