Database system

Question 1

SQL + sublanguages

Answer 1

Structured Query Language

• DML - Read and change stored data
• DDL - write and change data schema
• TCL- controlling and monitoring DML commands
• DCL - manages access rights

Question 2

Database over simple files

Answer 2

• Specific and easy-to-use functions
• Optimized for efficiency
• Simultaneous access
• Support fine-grained access protection
• Consistent state can normally be restored

Question 3

DBMSs

Answer 3

Standard database management system

Manages access and provides corresponding functions

Question 4

RDBMSs

Answer 4

Relational database management system

For the administration of relationally organized databases

Question 5

Artificial key

Answer 5

Additional attribute added to a relation that is used as a primary key. Artificial Key has no meaning outside of the table

Question 6

Foreign Key

Answer 6

References a primary key of another. Has to have referential integrity

Question 7

Referential integrity

Answer 7

A property of a database where by all foreign keys used are actually used as primary key in another table and thus a valid reference to another data record exists.

Question 8

Primary Key

Answer 8

A key that uniquely identifies and entity is called a primary key. Simple PK is formed by exactly 1 attribute. Composite PK is formed by several attributes. PK is never a NULL value

Question 9

SELECT + optional additions

Answer 9

Querying data from a table
General structure: SELECT name FROM country;
Optional additions:
WHERE
GROUP BY
HAVING
ORDER BY

Question 10

Logical operators

Answer 10

NOT
OR
AND

Question 11

comparison operators

Answer 11

=
<> or !=
> or <
>= or <=
BETWEEN
LIKE