A node can have any number of subordinates and superiors
A subordinate node must have many superiors
A superior may have one or many subordinates
Pregunta 2
Pregunta
In a table one can have:
Respuesta
A simple primary key
A composed primary key
A simple foreign key
A foreign primary key
A control key
Pregunta 3
Pregunta
The conceptual schema is the result of:
Respuesta
The system study
The system analysis
The application requirements
The database structure's design
The database functions' design
Pregunta 4
Pregunta
The clusters are useful for:
Respuesta
Optimizing the database
Requests
Updates
Data inserts
Documentary databases
Pregunta 5
Pregunta
A components database system architecture includes:
Respuesta
data
database management system
application programs
legal and administrative regulations
hardware
Pregunta 6
Pregunta
Having the table STUDENT ( name, year, group, no_stud_group, group_secretary, birth_date), what affirmation(s) is(are) not true:
Respuesta
The table is in 2NF
The table has a fully functionally dependence
The table has a non-transitive dependence
The table is normalized
The table has a composed primary key
Pregunta 7
Pregunta
In the relational model:
Respuesta
There is the "record" notion
The attributes that have a role in making the links between tables are called composed keys
The links between tables are described in DML
There is the "table schema" notion
Projection, negation and existential are relational algebra operators
Pregunta 8
Pregunta
Having the tables
PRODUCTS (product_id NUMBER(15) primary key, name VARCHAR2(25), price NUMBER (7, 2), release_date DATE),
ORDERS (order_id NUMBER(10) primary key, product_id NUMBER (15) REFERENCES products(product_id), quantity NUMBER(7,2), order_date DATE).
Select the orders that were made for the products that were released in 2000 (in two ways)
Respuesta
select o.order_id, p.name, p.release_date, o.quantity from products p, orders o where p.product_id = o.product_id and extract (year from p.release_date) = 2000;
select o.order_id, p.name, p.release_date, o.quantity from products p join orders o using(product_id) where to_char(p.release_date, 'DD.MM.YYYY') like '%2000';