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sdp 6

Descripción

Test sobre sdp 6 , creado por Жарас Мергазы el 16/12/2017.
Жарас Мергазы
Test por Жарас Мергазы, actualizado hace más de 1 año
Жарас Мергазы
Creado por Жарас Мергазы hace más de 6 años
969
10
0

Resumen del Recurso

Pregunta 1

Pregunta
The PEAR DB functions can be accessed using DB::<function_name>.
Respuesta
  • True
  • False

Pregunta 2

Pregunta
The string argument of the function for connecting to a database is of the format <DBMS software>://<user account>:<password>@<database server>
Respuesta
  • True
  • False

Pregunta 3

Pregunta
The PEAR DB functon for connecting to a database is called DB::linkto database('string').
Respuesta
  • True
  • False

Pregunta 4

Pregunta
• The DBMS software in <DBMS software>://<user account>:<password>@<database server> stands for the particular DBMS software package being connected to: for example mysqli for versions of MySQL starting with version 4.1.2
Respuesta
  • True
  • False

Pregunta 5

Pregunta
• The PEAR DB function DB::is Error can be used to determine whether any database access operation was successful or not.
Respuesta
  • True
  • False

Pregunta 6

Pregunta
• In PHP, an _____ array provides pairs of key=>value elements; the value of an element is referenced through its key and all key values in a particular array must be unique.
Respuesta
  • Numeric
  • Value
  • String
  • Associative

Pregunta 7

Pregunta
• Multi-line PHP comments start with // and end with #.
Respuesta
  • True
  • False

Pregunta 8

Pregunta
• PHP written in C and usually comes installed with Unix: for other operating systems, the PHP interpreter can be downloaded from http://www.php.net
Respuesta
  • True
  • False

Pregunta 9

Pregunta
• The PHP start tag is <?php and end the tag is ?>.
Respuesta
  • True
  • False

Pregunta 10

Pregunta
• Web pages, where part of the information is extracted from databases or other data source, are called dynamic Web pages
Respuesta
  • True
  • False

Pregunta 11

Pregunta
• In PHP, a ____ array associates a numeric index with each element in the array
Respuesta
  • Numeric
  • Associated
  • Variable
  • String

Pregunta 12

Pregunta
• PHP variable names start with a $ sign and can include characters, numbers, and the underscore character
Respuesta
  • True
  • False

Pregunta 13

Pregunta
• Interpolating variables occurs only within single-quoted strings.
Respuesta
  • True
  • False

Pregunta 14

Pregunta
• PHP programs are executed on the client.
Respuesta
  • True
  • False

Pregunta 15

Pregunta
• The auto-global predefined PHP variable $_POST is an array that holds all the values entered through form parameters.
Respuesta
  • True
  • False

Pregunta 16

Pregunta
• JDBC does not distinguish between queries that return single tuples and those that return multiple tuples.
Respuesta
  • True
  • False

Pregunta 17

Pregunta
• The JDBC _____ libraries are called java.sql.*
Respuesta
  • Method
  • Function
  • Class

Pregunta 18

Pregunta
• What are the advantages and disadvantages of the embedded SQL approach.
Respuesta
  • The main advantage is the query text is part of the source code can be checked for syntax errors and validated against the database schema at compile time. The program is quite readable. Since queries are known in advance, the choice of program variables to hold query results is simple.
  • The main advantage is flexibility in generating queries at runtime. Also, the library of function calls approach is able to call multiple data program.
  • The main disadvantage is the query text is part of the source code can be checked for syntax errors and validated against the database schema at compile time. The program is quite readable. Since queries are known in advance, the choice of program variables to hold query results is simple.
  • Disadvantage are more complex programming, inability to do checking at compile time, and concerns about SQL runtime errors.
  • Disadvantage are the loss of flexibility in changing the query the query at runtime and that all changes to queries must be recompiled.

Pregunta 19

Pregunta
• The use of function calls is a more dynamic approach for database programming than embedded SQL.
Respuesta
  • True
  • False

Pregunta 20

Pregunta
• A _____ object is similar to a cursor in embedded SQL and an iterator in SQLJ.
Respuesta
  • Procedure
  • Function call
  • Result Set

Pregunta 21

Pregunta
• _____ is the part of the SQL standard that specifies how to write persistent stored modules.
Respuesta
  • SQL/PSM
  • XML
  • SQLJ
  • ResultSet

Pregunta 22

Pregunta
• Database stored procedures (aka persistent stored modules) are stored and executed by the DBMS at the database server.
Respuesta
  • True
  • False

Pregunta 23

Pregunta
• Discuss advantages and diadvantages to the library of function calls approach
Respuesta
  • Disadvantage are the loss of flexibility in changing the query at runtime and that all changes to queries must be recompiled.
  • The main advantage is flexibility in generating queries at runtime. Also, the library of function calls approach is able to call multiple data program.
  • The main advantage is flexibility in generating queries at compile time. Also, the library of function calls approach is able to call multiple single program.
  • Disadvantages are more complex programming, inability to do checking at compile time, and concerns about SQL runtime errors.
  • The main advantage is the query text is part of source code and can be checked for syntax errors and validated against the data. The program is quite readable.

Pregunta 24

Pregunta
• It is necessary to have a binding between the data types of the programming language and the attribute data types in the data model
Respuesta
  • True
  • False

Pregunta 25

Pregunta
• In SQLJ, embedded SQL commands are preceded by #sql.
Respuesta
  • True
  • False

Pregunta 26

Pregunta
• One advantage of using an SQLJ translator is that it is not necessary to install drivers such as a JDBC driver.
Respuesta
  • True
  • False

Pregunta 27

Pregunta
• Describe the three main approaches for database programming.
Respuesta
  • • Using a library of database functions. This approach provides what is known as an application programming interface (API) for accessing a database from applications programs.
  • • Using a library of database methods. This approach provides what is known as an application programming interface (API) for accessing a database from applications programs
  • • Embedded SQL. Embeding database commands in a general-purpose programming language. A preprocessor extracts the embedded SQL from the source code and replaces it with function calls to DBMS-generated code.
  • • Embedded SQL. Embeding database commands in a specific-purpose programming language. A preprocessor can not extract code, but function calls to be extracted to DBMS-generated code.
  • • Designing a new database programming language.
  • • Embedded SQL. Embeding database commands in a specific-purpose programming language. A preprocessor extracts the embedded SQL from the source code and replaces it with function calls to DBMS-generating code

Pregunta 28

Pregunta
• In XML _____ defines the set of commands (names) that can be used
Respuesta
  • • Namespace
  • • Valid
  • • Document
  • • Invalid

Pregunta 29

Pregunta
• In XML schema, the tag _____ is used tospecify primary keys.
Respuesta
  • • xs:element
  • • xsd:key
  • • psd:schema
  • • xs:sequence

Pregunta 30

Pregunta
• A * following an element name means the element can be repeated zero or one times (an optional, single-valued, nonrepeating elements)
Respuesta
  • True
  • False

Pregunta 31

Pregunta
• If an XML document is well-formed and follows a particular schema, it is _____
Respuesta
  • • Namespace
  • • Keys
  • • Invalid
  • • Valid

Pregunta 32

Pregunta
• The XML schema, it is possible to specify constraints that correspond to unique and primary key constraints ina relational database, as well as foreign keys constraints
Respuesta
  • True
  • False

Pregunta 33

Pregunta
• An element that does not have *, +, or ? following the element name means the element must appear exactly once in the document (a required, single-valued, nonrepeating element).
Respuesta
  • True
  • False

Pregunta 34

Pregunta
• A ? following an element name means that element can be repeated zero or more times in the document (an optional, mult-valued, repeating element).
Respuesta
  • True
  • False

Pregunta 35

Pregunta
• The basic object in XML is the XML document, which is structured using types and iterators.
Respuesta
  • True
  • False

Pregunta 36

Pregunta
• How does a well-formed XML document look like?
Respuesta
  • • It is syntactically correct: a non-single root element with every element including a matching pair of start/end tags within the start-end of the parent element
  • • It must finish with an XML declaration to indicate the version of XML.
  • • It is syntactically correct: a single root element with every element including a matching pair of start/end tags within the start-end tags of the parent element
  • • It is syntactically correct: a single root element with every element except a matching pair of start/end tags within the start-end tags of the parent elements
  • • It must start with an XML declaration to indicate the version of XML

Pregunta 37

Pregunta
• Struct type constructors include the set (T), list (T), bag(T), array(T), and dictionary (K,T) type constructors.
Respuesta
  • True
  • False

Pregunta 38

Pregunta
• Three major differences between the relational and object database design.
Respuesta
  • • In ODB design a binary relationship can be declared in one direction or both. If attributes are included in both directions, there is a potential problem with redundancy.
  • • In ODB design a binary relationship can be declared in one direction or both. If attributes are included in both directions, there is no any problem
  • • In an ODB, operations must be defined early since they are part of the classes specifications. In RDBs, operations may not be defined until implementation
  • • In RDB inheritance is built into the model; ODBs do not have built-in constructs for inheritance.
  • • In an RDB, operations must be defined early since they are part of the class specifications. In an ODB, operations may not be defined until implementation
  • • In ODB inheritance is built into the model; RDBs do not have built-in constructs for inheritance.

Pregunta 39

Pregunta
• The typical mechanisms for making an object an object persistent are naming and reachability.
Respuesta
  • True
  • False

Pregunta 40

Pregunta
• The main property required of an OID is that it be immutable (should not change).
Respuesta
  • True
  • False

Pregunta 41

Pregunta
• _____ inheritance occurs when a subtype inherits only some of the functions of a supertype.
Respuesta
  • • Generalisation
  • • Complete encapsulation
  • • Conditional
  • • Selective

Pregunta 42

Pregunta
• In operator overloading (or polymorphism), an operation name may refer to several distinct implementations, depending on the type of object it is applied to.
Respuesta
  • True
  • False

Pregunta 43

Pregunta
• In ______ all operations that can be applied to an object must be predefined.
Respuesta
  • • Half encapsulation
  • • Complete encapsulation
  • • Object identifier
  • • Feedback loop

Pregunta 44

Pregunta
• The implementation of an operation is called its signature.
Respuesta
  • True
  • False

Pregunta 45

Pregunta
• A subtype is used when a new type is needed that is similar but not identical to an already defined type.
Respuesta
  • True
  • False

Pregunta 46

Pregunta
• The dictionary constructor creates a collection of two tupes (K,V) where the value of a key K can be used to retrieve the can be used to retrieve the corresponding value V.
Respuesta
  • True
  • False

Pregunta 47

Pregunta
• An ODMS provides a unique identity to each independent object in the database via a unique, system-generated ____.
Respuesta
  • • Selective
  • • Complete encaplsulation
  • • Object identifier

Pregunta 48

Pregunta
• An object typically has three components: state, timing, and behavior
Respuesta
  • True
  • False

Pregunta 49

Pregunta
• The 80-20 rule suggests that 80% of the workload is presented by 20% of the most frequently used transactions, which govem the physical database design.
Respuesta
  • True
  • False

Pregunta 50

Pregunta
• The phases (or activities) of the life cycle are not strictly in sequence; ______ are common among and within the phases of the life cycle.
Respuesta
  • • One-shot
  • • Requirements collection
  • • Feedback loop
  • • View integration

Pregunta 51

Pregunta
• In the _____ approach to schema design, a scheme is designed for each user group or application based phase, these schemas are merged into a global conecptual schema.
Respuesta
  • • Requirements analysis
  • • Feedback loops
  • • Feasibility analysis
  • • One-shot
  • • View integration

Pregunta 52

Pregunta
• A large database typically has large transaction volumes and rates, is used in service sector industries, and runs 24/7
Respuesta
  • True
  • False

Pregunta 53

Pregunta
• Many organizations use data dictionary systems (information repositories) to manage meta-data, i.e., data that describes the database structure, constraints, applications, authorizations, users, and so forth.
Respuesta
  • True
  • False

Pregunta 54

Pregunta
• What are the three goals of database design?
Respuesta
  • a) Satisfy the information content requirements of the generalised users and applications.
  • • Support result
  • • Provide a natural and easy-to-understand structuring of the information.
  • • Support processing requirements and any performance objectives.
  • • Satisfy the information content requirements ofthe specified users and applications.
  • • Provide a comlicated structuring of the information.

Pregunta 55

Pregunta
• _______ involves interacting with potential users and user groups to identify their particular problems and needs.
Respuesta
  • • view-integration
  • • requirements collection and analysis
  • • feasibility analysis
  • • one-shot
  • • feedback loop

Pregunta 56

Pregunta
• A transaction processing system can be characterized as one with several dozen gigabytes of data and a schema with more than 30 or 40 distinct entity types
Respuesta
  • True
  • False

Pregunta 57

Pregunta
• Identify the three criteria to guide the choice of physical database design options
Respuesta
  • • Space utisilation
  • • Availability of vendor services
  • • Transaction throughput
  • • Response time
  • • Familiarity of personnel with the system

Pregunta 58

Pregunta
• Identify the three factors to consider in choosing one DBMS over another
Respuesta
  • • Space utisilation
  • • Organization-wide adoption of a certain philosophy (data model, vendor, methodology, tools)
  • • Availability of vendor services
  • • Transaction throughput
  • • Response time
  • • Familiarity of personnel with the system

Pregunta 59

Pregunta
• _____ is concerned with analyzing potential application areas, identifying the economics of information gathering and dissemination, performing preiliminary cost-benefit studies, determining the complexity of data and processes, and setting up priorities among applications.
Respuesta
  • • Feasibility analysis
  • • Requirements collection and analysis
  • • View integration
  • • One-shot
  • • Feedback loops

Pregunta 60

Pregunta
• The initial requirements can be expected to be formal, complete, consistent, and correct.
Respuesta
  • True
  • False

Pregunta 61

Pregunta
• In the ______ schema design approach, the requirements from the different stakeholders are merged into a single set of requirements before the schema design begins.
Respuesta
  • • Requirements collection
  • • Feedback loop
  • • Centralized (or one-shot)
  • • Requirements analysis

Pregunta 62

Pregunta
• What two things does minimizing redundancy imply?
Respuesta
  • • Reducing the need for multiple updates to maintain consistency across multiple copies of the same information.
  • • Reducing the redundant information in tuples.
  • • Making sure the semantics of the attributes is clear in the schema
  • • Minimizing redundant storage of the same information
  • • Disallowing the possibility of generating spurious tuples

Pregunta 63

Pregunta
• Third normal form (3NF): R is 2NF and all non-prime attributes are transively dependent on the primary key.
Respuesta
  • True
  • False

Pregunta 64

Pregunta
• First normal from (1NF): the domain of an attribute must include only atomic (simple, indivisible, scalar) values and the value of any attribute ina tuple must be a single value from the domain of that attribute.
Respuesta
  • True
  • False

Pregunta 65

Pregunta
A functional dependency is a property of the relation schema R not of a particular legal relation state r or R, therefor it must understands the semantics of the attributes of R.
Respuesta
  • True
  • False

Pregunta 66

Pregunta
Second normal form (2NF): R is 1NF and every non-prime attribute A in R is fully functionally dependent on the primary key of R
Respuesta
  • True
  • False

Pregunta 67

Pregunta
What are four informal guidelines that may be used to measure the quality of a relation schema design?
Respuesta
  • Reducing the need for multiple updates to maintain consistency across multiple copies of the same information.
  • • Disallowing the possibility of generating spurious tuples.
  • • Reducing the redundant information in tuples
  • • Reducing the NULL values in tuples
  • • Making sure the semantics of the attributes is clear in the schema
  • • Minimizing redundant storage of the same information

Pregunta 68

Pregunta
Normalization of data can be considered a process of analyzing the given relation schemas based on their functional dependencies and primary keys to achieve closure on the domain space
Respuesta
  • True
  • False

Pregunta 69

Pregunta
When mapping a binary M:N relationship type R, create a new relation S to represent R, including as foreign key attributes in S the primary keys of the relations that are the perticipating entity types (their combination in S is the composite primary key of S).
Respuesta
  • True
  • False

Pregunta 70

Pregunta
The symbol σ (sigma) is used to denote the SELECT operator in the relational algebra
Respuesta
  • True
  • False

Pregunta 71

Pregunta
A EQUIJOIN uses any of the comparison operators =, <, ≤, >, ≥, or ≠.
Respuesta
  • True
  • False

Pregunta 72

Pregunta
The symbol π (pi) is used to denote the PROJECT operation in the relational algebra.
Respuesta
  • True
  • False

Pregunta 73

Pregunta
A THETA JOIN uses the comparison operator =
Respuesta
  • True
  • False

Pregunta 74

Pregunta
SQL is both a data definition language (DDL) and a data manipulation language (DML).
Respuesta
  • True
  • False

Pregunta 75

Pregunta
A key uniquely identifies a tuple in a relation
Respuesta
  • True
  • False

Pregunta 76

Pregunta
When the DELETE operation violates a contraint, the deletion must be rejected.
Respuesta
  • True
  • False

Pregunta 77

Pregunta
Semantic integrity constarint may be enforced using mechanisms called triggers and assertions.
Respuesta
  • True
  • False

Pregunta 78

Pregunta
If a multi-table query refers to two or more attributes with the same name, we must qualify the attribute name with the table name, e.g., TABLE.Attribute, to prevent ambiguity.
Respuesta
  • True
  • False

Pregunta 79

Pregunta
A relation schema may only have one key.
Respuesta
  • True
  • False

Pregunta 80

Pregunta
Tuples in a relation are ordered.
Respuesta
  • True
  • False

Pregunta 81

Pregunta
The DELETE operation can violate referential integrity.
Respuesta
  • True
  • False

Pregunta 82

Pregunta
The INSERT operation can violate domain constraints, key constraints, entity integrity, or referential integrity.
Respuesta
  • True
  • False

Pregunta 83

Pregunta
The theortical basis of the relation data model is set theory and first-order predicate logic.
Respuesta
  • True
  • False

Pregunta 84

Pregunta
Attributes that represent the same real-world concept must have identical names in different relations.
Respuesta
  • True
  • False

Pregunta 85

Pregunta
When the INSERT operation violates a constraint, the default option is to reject the insertion.
Respuesta
  • True
  • False

Pregunta 86

Pregunta
Attributes must have unique domains.
Respuesta
  • True
  • False

Pregunta 87

Pregunta
NULL values may mean value unknown, value exits but is not available, attribute does not apply to this tuple (value undefined).
Respuesta
  • True
  • False

Pregunta 88

Pregunta
All tuples in a relation must be distinct.
Respuesta
  • True
  • False

Pregunta 89

Pregunta
The $d->query function takes an SQL command as its string argument and sends it to the database server for execution.
Respuesta
  • True
  • False

Pregunta 90

Pregunta
The _____ is a collection of several libraries of functions for enhancing PHP.
Respuesta
  • DBMS
  • PHP Extension and Application Repository (PEAR)
  • MYSQL
  • PHP SQL

Pregunta 91

Pregunta
The _____ variable is similar to cursor and iterator variables.
Respuesta
  • $d->query
  • post
  • $r

Pregunta 92

Pregunta
The abend function can be used to terminate a PHP program if there is an error.
Respuesta
  • True
  • False

Pregunta 93

Pregunta
The PHP function $d->nextID creates a sequence of unique values for a particular table.
Respuesta
  • True
  • False

Pregunta 94

Pregunta
Creating a database design that only stores each logical data item in only one place in the database
Respuesta
  • Normalization
  • Relational data model
  • Data abstraction
  • Redundancy

Pregunta 95

Pregunta
Stores catalog information about schemas and constraints, design decisions, usage standards, application program descriptions, and user information
Respuesta
  • Data dictionary (or data repository system or information repository)
  • Relational data model
  • Atomicity property
  • Data abstraction

Pregunta 96

Pregunta
Data that is derived from the database files but not explicitly stored
Respuesta
  • Relationship
  • Relational data model
  • Virtual data
  • Virtual date

Pregunta 97

Pregunta
Represents an association among two or more entities
Respuesta
  • . Relationship
  • Relational data model
  • Data abstraction
  • Redundancy

Pregunta 98

Pregunta
Represents a database as a collection of tables, where each table can be stored as a separate file
Respuesta
  • Data abstraction
  • Atomicity property
  • Redundancy
  • Relational data model

Pregunta 99

Pregunta
Ensures that either all the database operations in a transaction are executed or none are
Respuesta
  • Atomicity property
  • Atomic property
  • Redundancy
  • Data abstraction

Pregunta 100

Pregunta
Storing the same data multiple times
Respuesta
  • Redundancy
  • Data abstraction
  • Relationship
  • Virtual data

Pregunta 101

Pregunta
Characteristic that allows program-data independence and program-operation independence
Respuesta
  • Redundancy
  • Data abstraction
  • Relationship
  • Relational data model

Pregunta 102

Pregunta
Choose correct answer
Image:
1 (binary/octet-stream)
Respuesta

Pregunta 103

Pregunta
Choose correct answer!!
Image:
1 (binary/octet-stream)
Respuesta

Pregunta 104

Pregunta
Choose one
Image:
12222 (binary/octet-stream)
Respuesta

Pregunta 105

Pregunta
is typically used to loop over the tuples in a query result
Respuesta
  • cursor
  • named
  • positional
  • Impedance mismatch

Pregunta 106

Pregunta
iterator is associated with a query result in SQLJ by listing the attribute names and types that appear in the query
Respuesta
  • named
  • cursor
  • Impedance mismatch
  • positional

Pregunta 107

Pregunta
iterator lists only the attribute types that appear in a query result in SQLJ.
Respuesta
  • positional
  • Impedance mismatch
  • named
  • cursor

Pregunta 108

Pregunta
is the term used to refer to the problems that occur because of differences between the database model and language model
Respuesta
  • Impedance mismatch
  • positional
  • named
  • cursor

Pregunta 109

Pregunta
Used to choose a subset of the tuples from a relation that satisfies a selection condition
Respuesta
  • • LEFT OUTER JOIN
  • • SELECT
  • • PROJECT
  • • JOIN
  • • INTERSECTION

Pregunta 110

Pregunta
Selects certain columns from the table and discards the other columns
Respuesta
  • • PROJECT
  • • SELECT
  • • LEFT OUTER JOIN
  • • JOIN
  • • INTERSECTION

Pregunta 111

Pregunta
= R S keeps every tuple in the first (left) relation R; if no matching tuples is found in S, then the attributes of S in the join filled with NULL values
Respuesta
  • • LEFT OUTER JOIN
  • • SELECT
  • • PROJECT
  • • JOIN
  • • INTERSECTION

Pregunta 112

Pregunta
R S in the relational algebra combines related tuples in R and S
Respuesta
  • • JOIN
  • • INTERSECTION
  • • LEFT OUTER JOIN
  • • PROJECT
  • • SELECT

Pregunta 113

Pregunta
R S in the relational algebra includes all tuples in both R and S
Respuesta
  • • JOIN
  • • INTERSECTION
  • • LEFT OUTER JOIN
  • • PROJECT
  • • SELECT
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