6179153
Questão 1
Questão
1) The practical significance of taking the logical view of a database is that is serves as reminder of the simple file concept of data storage.
Responda
- True
- False
Questão 2
Questão
2) You can think of a table as a persistent representation of a logical relation.
Responda
- True
- False
Questão 3
Questão
3) Because the relational model uses attribute values to establish relationships among tables, many data-base susers correctly assume that the term relation refers to such relationships.
Responda
- True
- False
Questão 4
Questão
4) The order of the rows and columns is important to the DBMS.
Responda
- True
- False
Questão 5
Questão
5) Numeric data are data on which you can perform meaningful arithmetic procedures.
Responda
- True
- False
Questão 6
Questão
6) Character data can contain any character or symbol intended for mathematical manipulation.
Responda
- True
- False
Questão 7
Questão
7) Each table in a relational database must have a primary key.
Responda
- True
- False
Questão 8
Questão
8) The idea of determination is unique to the database environment.
Responda
- True
- False
Questão 9
Questão
9) In a relational model, if A determines B, C, and D, you write A = B, C, D.
Responda
- True
- False
Questão 10
Questão
10) Only a single attribute, not multiple attributes, can define functional dependence.
Responda
- True
- False
Questão 11
Questão
11) If the attribute (B) is functionally dependent on a composite key (A) but not on any subset of that composite key, the attribute (B) is fully functionally dependent on (A).
Responda
- True
- False
Questão 12
Questão
12) A null is created when you press the Enter key or the Tab key to move to the next entry without making a prior entry of any kind.
Responda
- True
- False
Questão 13
Questão
13) There is never a good reason to use null values in a database.
Responda
- True
- False
Questão 14
Questão
14) Depending on the sophistication of the application development software, nulls can create problems when functions such as COUNT, AVERAGE, and SUM are used.
Responda
- True
- False
Questão 15
Questão
15) Tables within a database share common attributes that enable the tables to be linked together.
Responda
- True
- False
Questão 16
Questão
16) A foreign key must exist in both tables that have a relationship
Responda
- True
- False
Questão 17
Questão
17) RDBMSs enforce integrity rules automatically.
Responda
- True
- False
Questão 18
Questão
18) Referential and entity integrity are two names for the same thing.
Responda
- True
- False
Questão 19
Questão
19) The SELECT operator yields a vertical subset of a table.
Responda
- True
- False
Questão 20
Questão
20) Tables must have the same attribute characteristics (the columns and domains must be compatible) to be used in a UNION.
Responda
- True
- False
Questão 21
Questão
21) The DIFFERENCE operator subtracts one table from the other.
Responda
- True
- False
Questão 22
Questão
22) In a natural join, the column on which the join was made occurs twice in the new table.
Responda
- True
- False
Questão 23
Questão
23) A left outer join on tables CUSTOMER and AGENT yields all of the rows in the CUSTOMER table, including those that do not have a matching value in the AGENT table.
Responda
- True
- False
Questão 24
Questão
24) The DIVIDE operation uses one single-column table (e.g., column "a") as the divsor and one two-column table (e.g., columns "a" and "b") as the dividend.
Responda
- True
- False
Questão 25
Questão
25) A data dictionary contains metadata-data about data.
Responda
- True
- False
Questão 26
Questão
26) A data dictionary is sometimes described as :the database designer's database" because it records the design decisions about tables and their structures.
Responda
- True
- False
Questão 27
Questão
27) Current relational database software generally provides only a system catalog (and not a data dictionary).
Responda
- True
- False
Questão 28
Questão
28) The one-to-many (1:M) relationship is easily implemented in the relational mode by putting the foreign key of the "1" side in the table of the "many" side as a primary key.
Responda
- True
- False
Questão 29
Questão
29) As rare as 1:! relationships should be, certain conditions absolutely require their use.
Responda
- True
- False
Questão 30
Questão
30) DBMSs use indexes for many different purposes.
Responda
- True
- False
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