Questão 1
Questão
The PEAR DB functions can be accessed using DB::<function_name>.
Questão 2
Questão
The string argument of the function for connecting to a database is of the format <DBMS software>://<user account>:<password>@<database server>
Questão 3
Questão
The PEAR DB functon for connecting to a database is called DB::linkto database('string').
Questão 4
Questão
• 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
Questão 5
Questão
• The PEAR DB function DB::is Error can be used to determine whether any database access operation was successful or not.
Questão 6
Questão
• 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.
Responda
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Numeric
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Value
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String
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Associative
Questão 7
Questão
• Multi-line PHP comments start with // and end with #.
Questão 8
Questão
• 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
Questão 9
Questão
• The PHP start tag is <?php and end the tag is ?>.
Questão 10
Questão
• Web pages, where part of the information is extracted from databases or other data source, are called dynamic Web pages
Questão 11
Questão
• In PHP, a ____ array associates a numeric index with each element in the array
Responda
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Numeric
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Associated
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Variable
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String
Questão 12
Questão
• PHP variable names start with a $ sign and can include characters, numbers, and the underscore character
Questão 13
Questão
• Interpolating variables occurs only within single-quoted strings.
Questão 14
Questão
• PHP programs are executed on the client.
Questão 15
Questão
• The auto-global predefined PHP variable $_POST is an array that holds all the values entered through form parameters.
Questão 16
Questão
• JDBC does not distinguish between queries that return single tuples and those that return multiple tuples.
Questão 17
Questão
• The JDBC _____ libraries are called java.sql.*
Questão 18
Questão
• What are the advantages and disadvantages of the embedded SQL approach.
Responda
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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.
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The main advantage is flexibility in generating queries at runtime. Also, the library of function calls approach is able to call multiple data program.
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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.
Questão 19
Questão
• The use of function calls is a more dynamic approach for database programming than embedded SQL.
Questão 20
Questão
• A _____ object is similar to a cursor in embedded SQL and an iterator in SQLJ.
Responda
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Procedure
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Function call
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Result Set
Questão 21
Questão
• _____ is the part of the SQL standard that specifies how to write persistent stored modules.
Responda
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SQL/PSM
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XML
-
SQLJ
-
ResultSet
Questão 22
Questão
• Database stored procedures (aka persistent stored modules) are stored and executed by the DBMS at the database server.
Questão 23
Questão
• Discuss advantages and diadvantages to the library of function calls approach
Responda
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Disadvantage are the loss of flexibility in changing the query at runtime and that all changes to queries must be recompiled.
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The main advantage is flexibility in generating queries at runtime. Also, the library of function calls approach is able to call multiple data program.
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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.
Questão 24
Questão
• It is necessary to have a binding between the data types of the programming language and the attribute data types in the data model
Questão 25
Questão
• In SQLJ, embedded SQL commands are preceded by #sql.
Questão 26
Questão
• One advantage of using an SQLJ translator is that it is not necessary to install drivers such as a JDBC driver.
Questão 27
Questão
• Describe the three main approaches for database programming.
Responda
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• 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.
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• 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
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• 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.
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• 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.
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• Designing a new database programming language.
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• 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
Questão 28
Questão
• In XML _____ defines the set of commands (names) that can be used
Responda
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• Namespace
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• Valid
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• Document
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• Invalid
Questão 29
Questão
• In XML schema, the tag _____ is used tospecify primary keys.
Responda
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• xs:element
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• xsd:key
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• psd:schema
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• xs:sequence
Questão 30
Questão
• A * following an element name means the element can be repeated zero or one times (an optional, single-valued, nonrepeating elements)
Questão 31
Questão
• If an XML document is well-formed and follows a particular schema, it is _____
Responda
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• Namespace
-
• Keys
-
• Invalid
-
• Valid
Questão 32
Questão
• 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
Questão 33
Questão
• 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).
Questão 34
Questão
• A ? following an element name means that element can be repeated zero or more times in the document (an optional, mult-valued, repeating element).
Questão 35
Questão
• The basic object in XML is the XML document, which is structured using types and iterators.
Questão 36
Questão
• How does a well-formed XML document look like?
Responda
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• 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
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• It must finish with an XML declaration to indicate the version of XML.
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• 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
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• 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
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• It must start with an XML declaration to indicate the version of XML
Questão 37
Questão
• Struct type constructors include the set (T), list (T), bag(T), array(T), and dictionary (K,T) type constructors.
Questão 38
Questão
• Three major differences between the relational and object database design.
Responda
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• 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.
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• 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
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• 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
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• In RDB inheritance is built into the model; ODBs do not have built-in constructs for inheritance.
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• 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
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• In ODB inheritance is built into the model; RDBs do not have built-in constructs for inheritance.
Questão 39
Questão
• The typical mechanisms for making an object an object persistent are naming and reachability.
Questão 40
Questão
• The main property required of an OID is that it be immutable (should not change).
Questão 41
Questão
• _____ inheritance occurs when a subtype inherits only some of the functions of a supertype.
Responda
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• Generalisation
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• Complete encapsulation
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• Conditional
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• Selective
Questão 42
Questão
• In operator overloading (or polymorphism), an operation name may refer to several distinct implementations, depending on the type of object it is applied to.
Questão 43
Questão
• In ______ all operations that can be applied to an object must be predefined.
Responda
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• Half encapsulation
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• Complete encapsulation
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• Object identifier
-
• Feedback loop
Questão 44
Questão
• The implementation of an operation is called its signature.
Questão 45
Questão
• A subtype is used when a new type is needed that is similar but not identical to an already defined type.
Questão 46
Questão
• 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.
Questão 47
Questão
• An ODMS provides a unique identity to each independent object in the database via a unique, system-generated ____.
Questão 48
Questão
• An object typically has three components: state, timing, and behavior
Questão 49
Questão
• 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.
Questão 50
Questão
• The phases (or activities) of the life cycle are not strictly in sequence; ______ are common among and within the phases of the life cycle.
Questão 51
Questão
• 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.
Responda
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• Requirements analysis
-
• Feedback loops
-
• Feasibility analysis
-
• One-shot
-
• View integration
Questão 52
Questão
• A large database typically has large transaction volumes and rates, is used in service sector industries, and runs 24/7
Questão 53
Questão
• 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.
Questão 54
Questão
• What are the three goals of database design?
Responda
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a) Satisfy the information content requirements of the generalised users and applications.
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• Support result
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• Provide a natural and easy-to-understand structuring of the information.
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• Support processing requirements and any performance objectives.
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• Satisfy the information content requirements ofthe specified users and applications.
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• Provide a comlicated structuring of the information.
Questão 55
Questão
• _______ involves interacting with potential users and user groups to identify their particular problems and needs.
Questão 56
Questão
• 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
Questão 57
Questão
• Identify the three criteria to guide the choice of physical database design options
Questão 58
Questão
• Identify the three factors to consider in choosing one DBMS over another
Responda
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• Space utisilation
-
• Organization-wide adoption of a certain philosophy (data model, vendor, methodology, tools)
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• Availability of vendor services
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• Transaction throughput
-
• Response time
-
• Familiarity of personnel with the system
Questão 59
Questão
• _____ 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.
Questão 60
Questão
• The initial requirements can be expected to be formal, complete, consistent, and correct.
Questão 61
Questão
• In the ______ schema design approach, the requirements from the different stakeholders are merged into a single set of requirements before the schema design begins.
Questão 62
Questão
• What two things does minimizing redundancy imply?
Responda
-
• Reducing the need for multiple updates to maintain consistency across multiple copies of the same information.
-
• Reducing the redundant information in tuples.
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• Making sure the semantics of the attributes is clear in the schema
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• Minimizing redundant storage of the same information
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• Disallowing the possibility of generating spurious tuples
Questão 63
Questão
• Third normal form (3NF): R is 2NF and all non-prime attributes are transively dependent on the primary key.
Questão 64
Questão
• 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.
Questão 65
Questão
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.
Questão 66
Questão
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
Questão 67
Questão
What are four informal guidelines that may be used to measure the quality of a relation schema design?
Responda
-
Reducing the need for multiple updates to maintain consistency across multiple copies of the same information.
-
• Disallowing the possibility of generating spurious tuples.
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• Reducing the redundant information in tuples
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• Reducing the NULL values in tuples
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• Making sure the semantics of the attributes is clear in the schema
-
• Minimizing redundant storage of the same information
Questão 68
Questão
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
Questão 69
Questão
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).
Questão 70
Questão
The symbol σ (sigma) is used to denote the SELECT operator in the relational algebra
Questão 71
Questão
A EQUIJOIN uses any of the comparison operators =, <, ≤, >, ≥, or ≠.
Questão 72
Questão
The symbol π (pi) is used to denote the PROJECT operation in the relational algebra.
Questão 73
Questão
A THETA JOIN uses the comparison operator =
Questão 74
Questão
SQL is both a data definition language (DDL) and a data manipulation language (DML).
Questão 75
Questão
A key uniquely identifies a tuple in a relation
Questão 76
Questão
When the DELETE operation violates a contraint, the deletion must be rejected.
Questão 77
Questão
Semantic integrity constarint may be enforced using mechanisms called triggers and assertions.
Questão 78
Questão
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.
Questão 79
Questão
A relation schema may only have one key.
Questão 80
Questão
Tuples in a relation are ordered.
Questão 81
Questão
The DELETE operation can violate referential integrity.
Questão 82
Questão
The INSERT operation can violate domain constraints, key constraints, entity integrity, or referential integrity.
Questão 83
Questão
The theortical basis of the relation data model is set theory and first-order predicate logic.
Questão 84
Questão
Attributes that represent the same real-world concept must have identical names in different relations.
Questão 85
Questão
When the INSERT operation violates a constraint, the default option is to reject the insertion.
Questão 86
Questão
Attributes must have unique domains.
Questão 87
Questão
NULL values may mean value unknown, value exits but is not available, attribute does not apply to this tuple (value undefined).
Questão 88
Questão
All tuples in a relation must be distinct.
Questão 89
Questão
The $d->query function takes an SQL command as its string argument and sends it to the database server for execution.
Questão 90
Questão
The _____ is a collection of several libraries of functions for enhancing PHP.
Questão 91
Questão
The _____ variable is similar to cursor and iterator variables.
Questão 92
Questão
The abend function can be used to terminate a PHP program if there is an error.
Questão 93
Questão
The PHP function $d->nextID creates a sequence of unique values for a particular table.
Questão 94
Questão
Creating a database design that only stores each logical data item in only one place in the database
Responda
-
Normalization
-
Relational data model
-
Data abstraction
-
Redundancy
Questão 95
Questão
Stores catalog information about schemas and constraints, design decisions, usage standards, application program descriptions, and user information
Questão 96
Questão
Data that is derived from the database files but not explicitly stored
Responda
-
Relationship
-
Relational data model
-
Virtual data
-
Virtual date
Questão 97
Questão
Represents an association among two or more entities
Responda
-
. Relationship
-
Relational data model
-
Data abstraction
-
Redundancy
Questão 98
Questão
Represents a database as a collection of tables, where each table can be stored as a separate file
Responda
-
Data abstraction
-
Atomicity property
-
Redundancy
-
Relational data model
Questão 99
Questão
Ensures that either all the database operations in a transaction are executed or none are
Responda
-
Atomicity property
-
Atomic property
-
Redundancy
-
Data abstraction
Questão 100
Questão
Storing the same data multiple times
Responda
-
Redundancy
-
Data abstraction
-
Relationship
-
Virtual data
Questão 101
Questão
Characteristic that allows program-data independence and program-operation independence
Responda
-
Redundancy
-
Data abstraction
-
Relationship
-
Relational data model
Questão 102
Questão
Choose correct answer
Questão 103
Questão
Choose correct answer!!
Questão 104
Questão 105
Questão
is typically used to loop over the tuples in a query result
Responda
-
cursor
-
named
-
positional
-
Impedance mismatch
Questão 106
Questão
iterator is associated with a query result in SQLJ by listing the attribute names and types that appear in the query
Responda
-
named
-
cursor
-
Impedance mismatch
-
positional
Questão 107
Questão
iterator lists only the attribute types that appear in a query result in SQLJ.
Responda
-
positional
-
Impedance mismatch
-
named
-
cursor
Questão 108
Questão
is the term used to refer to the problems that occur because of differences between the database model and language model
Responda
-
Impedance mismatch
-
positional
-
named
-
cursor
Questão 109
Questão
Used to choose a subset of the tuples from a relation that satisfies a selection condition
Responda
-
• LEFT OUTER JOIN
-
• SELECT
-
• PROJECT
-
• JOIN
-
• INTERSECTION
Questão 110
Questão
Selects certain columns from the table and discards the other columns
Responda
-
• PROJECT
-
• SELECT
-
• LEFT OUTER JOIN
-
• JOIN
-
• INTERSECTION
Questão 111
Questão
= 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
Responda
-
• LEFT OUTER JOIN
-
• SELECT
-
• PROJECT
-
• JOIN
-
• INTERSECTION
Questão 112
Questão
R S in the relational algebra combines related tuples in R and S
Responda
-
• JOIN
-
• INTERSECTION
-
• LEFT OUTER JOIN
-
• PROJECT
-
• SELECT
Questão 113
Questão
R S in the relational algebra includes all tuples in both R and S
Responda
-
• JOIN
-
• INTERSECTION
-
• LEFT OUTER JOIN
-
• PROJECT
-
• SELECT