An attribute is a(n): a. Two-dimensional table. b. column of a table c. row of a
ID: 3803228 • Letter: A
Question
An attribute is a(n):
a.
Two-dimensional table.
b.
column of a table
c.
row of a table
the set of permitted values for each attribute
a.
Domain
b.
Dashed lines
c.
Rectangles
Output all pairs of rows from the two input relations
a.
Natural join
b.
Cartesian product
c.
Unoin
Output pairs of rows from the two input relations that have the same value on all attributes that have the same name
a.
Union
b.
Natural join
c.
Cartesian product
____ computes the join and then adds tuples form one relation that does not match tuples in the other relation to the result of the join.
1.
join
2.
outer join
3.
cartesian product
4.
Natural Join
In relation algebra, the symbol U is
a.
Set different
b.
Union
c.
Set intersection
In relation algebra, the symbol - is
a.
Set intersection
b.
Set different
c.
Union
Drawbacks of using file systems to store data
a.
Data redundancy and inconsistency
b.
Data isolation
c.
Difficulty in accessing data
d.
all above
.......……. the logical structure of the database
a.
Schema
b.
Instance
c.
Relation
d.
Diagram
…………. is a program module that provides the interface between the low-level data stored in the database and the application programs and queries submitted to the system.
a.
Storage manager
b.
Transection
c.
SQL
d.
Transaction manager
a.
Two-dimensional table.
b.
column of a table
c.
row of a table
Explanation / Answer
1. An attribute is a collumn in relation.
2. The set of permitted values for each attributes is Domain
3. Output all pairs of rows from the two input relations - Cartesian Product
Cartesian product gives all possible combinations of rows from two relations.
4.Output pairs of rows from the two input relations that have the same value on all attributes that have the same name - Union
5.Outer Join computes the join and then adds tuples form one relation that does not match tuples in the other relation to the result of the join.
6. In relation algebra, the symbol U is Union Operator
7. In relation algebra, the symbol - is Set Difference
8. Drawbacks of using file systems to store data - Data redundancy and inconsistancy
while using file system if you insert any duplicate data it never restrict you to do so and thus you end up entering the same data that is already available in the file.
File also doen't support consistancy.
9. Schema the logical structure of the database
10. Storage Manager is a program module that provides the interface between the low-level data stored in the sdatabase and the application programs and querie submitted to the system.
-> interaction with the file manager
-> efficient storing, retrieving and updating of data
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