6179153
Pregunta 1
Pregunta
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.
Respuesta
- True
- False
Pregunta 2
Pregunta
2) You can think of a table as a persistent representation of a logical relation.
Respuesta
- True
- False
Pregunta 3
Pregunta
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.
Respuesta
- True
- False
Pregunta 4
Pregunta
4) The order of the rows and columns is important to the DBMS.
Respuesta
- True
- False
Pregunta 5
Pregunta
5) Numeric data are data on which you can perform meaningful arithmetic procedures.
Respuesta
- True
- False
Pregunta 6
Pregunta
6) Character data can contain any character or symbol intended for mathematical manipulation.
Respuesta
- True
- False
Pregunta 7
Pregunta
7) Each table in a relational database must have a primary key.
Respuesta
- True
- False
Pregunta 8
Pregunta
8) The idea of determination is unique to the database environment.
Respuesta
- True
- False
Pregunta 9
Pregunta
9) In a relational model, if A determines B, C, and D, you write A = B, C, D.
Respuesta
- True
- False
Pregunta 10
Pregunta
10) Only a single attribute, not multiple attributes, can define functional dependence.
Respuesta
- True
- False
Pregunta 11
Pregunta
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).
Respuesta
- True
- False
Pregunta 12
Pregunta
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.
Respuesta
- True
- False
Pregunta 13
Pregunta
13) There is never a good reason to use null values in a database.
Respuesta
- True
- False
Pregunta 14
Pregunta
14) Depending on the sophistication of the application development software, nulls can create problems when functions such as COUNT, AVERAGE, and SUM are used.
Respuesta
- True
- False
Pregunta 15
Pregunta
15) Tables within a database share common attributes that enable the tables to be linked together.
Respuesta
- True
- False
Pregunta 16
Pregunta
16) A foreign key must exist in both tables that have a relationship
Respuesta
- True
- False
Pregunta 17
Pregunta
17) RDBMSs enforce integrity rules automatically.
Respuesta
- True
- False
Pregunta 18
Pregunta
18) Referential and entity integrity are two names for the same thing.
Respuesta
- True
- False
Pregunta 19
Pregunta
19) The SELECT operator yields a vertical subset of a table.
Respuesta
- True
- False
Pregunta 20
Pregunta
20) Tables must have the same attribute characteristics (the columns and domains must be compatible) to be used in a UNION.
Respuesta
- True
- False
Pregunta 21
Pregunta
21) The DIFFERENCE operator subtracts one table from the other.
Respuesta
- True
- False
Pregunta 22
Pregunta
22) In a natural join, the column on which the join was made occurs twice in the new table.
Respuesta
- True
- False
Pregunta 23
Pregunta
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.
Respuesta
- True
- False
Pregunta 24
Pregunta
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.
Respuesta
- True
- False
Pregunta 25
Pregunta
25) A data dictionary contains metadata-data about data.
Respuesta
- True
- False
Pregunta 26
Pregunta
26) A data dictionary is sometimes described as :the database designer's database" because it records the design decisions about tables and their structures.
Respuesta
- True
- False
Pregunta 27
Pregunta
27) Current relational database software generally provides only a system catalog (and not a data dictionary).
Respuesta
- True
- False
Pregunta 28
Pregunta
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.
Respuesta
- True
- False
Pregunta 29
Pregunta
29) As rare as 1:! relationships should be, certain conditions absolutely require their use.
Respuesta
- True
- False
Pregunta 30
Pregunta
30) DBMSs use indexes for many different purposes.
Respuesta
- True
- False
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