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Preguntas del test (160)
1In a database system, whose responsibility is it to provide data consistency?
- Athe application programmer's
- Bthe DBMS's
- Cthe database administrator's
- Dthe user's
2The physical storage structure will be _____ to the application programmer in a database approach, and will be _____ to the application programmer in a file system approach.
- Ahidden, hidden
- Bhidden, visible
- Cvisible, visible
- Dvisible, hidden
3What information is necessary when specifying the structure of a table?
- Athe name of the table and the names of the table's attributes
- Bthe name of the table, the names of the table's attributes, the data types of the table's attributes, the formats of the table's attributes, and the maximum number of rows that the table can have
- Cthe name of the table, the names of the table's attributes, the data types of attributes, and the formats of attributes
- Dthe name of the table and the amount of storage space to be allocated to the table
4The degree of a table is the number of _____ in the table.
- Arows
- Bforeign keys
- CKeys
- Dcolumns
5The cardinality of a table is the number of _____ in the table.
- Akeys
- Brows
- Cforeign keys
- Dcolumns
6A join operation joins _____ tables into _____.
- Atwo, one
- Bthree, two
- Cfour, two
- Dthree, one
7DDL is used to
- Aspecify the structure of a database.
- Bdefine the structure of database applications.
- Cadd contents to tables.
- Daccess the contents of tables.
8DML is used to
- Amanipulate the structure of database applications.
- Badd/modify/delete data in the database.
- Cadd and delete tables.
- Dspecify the structure of a database.
9The SQL clause to perform a set difference operation is
- ADIFFER
- BOMIT
- CEXCEPT
- DREJECT
10The SQL clause to perform a set UNION operation is
- AUNION
- BMELD
- CUNITE
- DCOMBINE
11With Query By Example, a user enters a query by
- Awriting an English description of the data that the user needs
- Bfilling in skeleton tables of the database with examples of what is to be retrieved
- Cplacing SQL keywords, such as select, under the column names they want to retrieve
- Dtyping a syntactically correct SQL query that uses column and table names similar to the correct column and table names in a database
12When removing a table from the schema, using the RESTRICT option would
- Aremove the table and all references to it
- Brecursively remove the table and all other tables that the removed table refers to
- Cremove the table if there are no references to it
- Dremove the table and all other tables that the specified table refers to
13In SQL, when destroying a database, the RESTRICT option removes
- Athe data and schema from the specified database, but not from related databases
- Beverything in the specified database: the data, schema, etc.
- Cthe data but not the schema
- Dthe schema if the database has no data (empty tables)
14In SQL, one function of the AS operator is to
- Alimit the cardinality of a relation
- Bcustomize the names of columns in a query’s result
- Cdefine the domain of an attribute
- Dcontrol the order in which a query’s rows are sorted
15In SQL, a database can be created by which of the following?
- Athe command INSERT DATABASE
- Ba series of CREATE TABLE commands
- Cthe command ADD DATABASE
- Dthe command CREATE SCHEMA
16In SQL, a database can be destroyed by which of the following?
- Athe command DESTROY DATABASE
- Ba series of DESTROY TABLE commands
- Cthe command DROP SCHEMA
- Dthe command DELETE DATABASE
17In SQL, which of the following operators can be used to express searches that test for a range in a selection condition?
- AFROM and TO
- BBETWEEN
- CSTART and END
- DRANGE
18In SQL, which of the following clauses can be used to sort results in ascending or descending order of attribute values?
- AORDER BY
- BSORT
- CARRANGE BY
- DGROUP BY
19In a FROM clause of a SELECT statement in SQL, a table can be aliased with which of the following operators?
- AAS
- B@
- CALIAS
- DRENAME
20When specifying a selection criterion in SQL, attributes can be renamed with which of the following operators?
- AAS
- B@
- CALIAS
- DRENAME
21Which of the following is true about updateability of views?
- AA view is not updateable if it involves one table and contains a key.
- BA view is updateable under all circumstances.
- CA view is not updateable if it involves aggregate functions and nested queries.
- DA view is not updateable under any circumstance.
22The SQL keyword _____ makes the modifications of the transaction permanent, while the SQL keyword _____ discards the modifications of the transaction.
- AWRITE, ABORT
- BCOMMIT, ROLLBACK
- CUPDATE, SELECT
- DSAVE, CANCEL
23Consider two tables, Employee(EmpNo, Name, DeptNo) and Department(DeptNo, Name, Manager) with primary keys being EmpNo and DeptNo respectively. The DeptNo attribute of the Employee table has a NOT NULL constraint and is a foreign key that references the DeptNo attribute of the Department table. The Manager attribute of the Department table has a NOT NULL constraint and is a foreign key that references the EmpNo attribute of the Employee table. When the tables are empty, the only way to insert rows into the two tables is
- Ato use a transaction in NOT DEFERRABLE mode
- Bto use a transaction either in DEFERRABLE mode or in NOT DEFERRABLE mode
- Cnot to use a transaction at all
- Dto use a transaction in DEFERRABLE mode
24Which of the following commands can be used to remove access privileges associated with a table?
- AREVOKE
- BDENY
- CRETRACT
- DREMOVE
25Which of the following commands can be used to give access permissions to a table?
- AGRANT
- BAUTHORIZE
- CPERMIT
- DALLOW
26Who can always give access permissions to a table?
- Aonly the super-user
- Bthe owner of the table
- Cthe user of the table
- Donly the database administrator (DBA)
27When is embedded SQL referred to as dynamic SQL?
- Awhen the embedded SQL is translated into DBMS calls at run-time
- Bwhen the embedded SQL operates on the dynamic part of the database
- Cwhen the embedded SQL always returns different sets of results
- Dwhen the SQL statements are changed in every ru
28When is embedded SQL referred to as static SQL?
- Awhen the SQL statements can never be changed
- Bwhen the embedded SQL operates on the static part of the database
- Cwhen the embedded SQL always returns the same set of results
- Dwhen the embedded SQL is translated into DBMS calls at compile-time
29In the relational model, which of the following is true about the data type of a column?
- AIt need not be atomic and it cannot be an abstract data type.
- BIt must be atomic and it can be an abstract data type.
- CIt must be atomic and it cannot be an abstract data type.
- DIt need not be atomic and it can be an abstract data type.
30Which of the following is true about the number of primary keys and alternate keys with respect to a table?
- AThere can be only one primary key, but many alternate keys.
- BThere can be many primary keys and many alternate keys.
- CThere can be only one primary key and only one alternate key.
- DThere can be many primary keys, but only one alternate key.
31The result of a set difference operation r - s will be
- Athose tuples that are in r but not in s
- Btuples in r after deducting their values by the corresponding values in the tuples in s
- Cthose tuples that are in s but not in r
- Dtuples in s after deducting their values by the corresponding values in the tuples in r
32An insertion operation will _____ if the insertion violates the uniqueness property of a key.
- Afail
- Bcrash the system
- Csucceed without warning
- Dsucceed with warning
33What does a projection operation do?
- AIt selects columns from a table.
- BIt selects rows from a table.
- CIt extends the number of rows in a table.
- DIt extends the number of columns in a table.
34Which of the following is true about primary keys and foreign keys holding NULL value?
- AA primary key cannot hold a NULL value and a foreign key cannot hold a NULL value
- BA primary key can hold a NULL value and a foreign key can hold a NULL value
- CA primary key cannot hold a NULL value and a foreign key can hold a NULL value
- DA primary key can hold a NULL value and a foreign key cannot hold a NULL value
35An insertion operation will _____ if the inserted primary key has a NULL value.
- Afail
- Bcrash the system
- Csucceed with warning
- Dsucceed without warning
36For two tables to be union compatible, corresponding columns from each table should have which of the following?
- Athe same domain
- Bthe same name
- Cdifferent names
- Ddifferent domains
37What is an alternate key?
- AA key that was added to the table after the table was designed
- BThe key to use when the primary key does not work
- CAny key that is not a primary key
- DA key that will become the primary key when the primary key is deleted
38With respect to a relational table, what is a key?
- AThe one column that uniquely identifies a row in the table
- BThe ID and password needed to access the table
- CA minimal subset of columns that uniquely identifies a row in the table
- DThe subset of all the rows and columns in the table that are visible to all users in the database system
39In a transaction, COMMIT specifies that
- Aall updates (including inserts, deletes, modifications) of a transaction are about to be made permanent in the database
- Ball updates (including inserts, deletes, modifications) of a transaction are to be made permanent in the database
- Conly the inserts and deletes of a transaction are to be made permanent in the database
- Donly the inserts and deletes of a transaction are about to be made permanent in the database
40Which of the following is true about the physical storage of tables defined by views?
- AExtra physical storage is always needed to store tables that a view defines.
- BExtra physical storage is needed to store tables that a view defines, only when rows are inserted into the view.
- CExtra physical storage is needed for storing the tables defined by views, only if views define additional non-existing columns.
- DThere is no extra physical storage needed to store tables that a view defines.
41When a string whose length is strictly less than n is entered as the value of a field whose SQL data type is CHAR(n), the system responds by
- Apadding the end of the string with NULL characters to length n before storing it
- Bre-prompting for the entry of a string whose length is exactly n
- Cpadding the end of the string with spaces to length n before storing it
- Dstoring the string as is
42In SQL, which of the following operators are used to check for set membership in a SELECT statement?
- AIN and NOT IN
- BSUBSET and NOT SUBSET
- CCOMPONENT and NOT COMPONENT
- DMEMBER and NOT MEMBER
43In contrast to _____ tables, a view refers to _____.
- Anon-empty, empty tables
- Bbase, a virtual table
- Cvirtual, base tables
- Dempty, non-empty tables
44When removing a table from the schema, using the CASCADE option would
- Aremove the table and all other tables that the specified table refers to.
- Bremove the table if there are no references to it
- Crecursively remove the table and all other tables that the removed table refers to
- Dremove the table and all references to it
45In SQL, the results of a _____ statement can be used to process a _____ statement.
- AINSERT, DELETE
- BINSERT, SELECT
- CSELECT, INSERT
- DDELETE, INSERT
46Which of the following SQL commands can be used to destroy and remove a table from the schema?
- ADROP TABLE
- BREMOVE TABLE
- CDELETE TABLE
- DDESTROY TABLE
47Which of the following SQL commands can be used to change, add, or drop column definitions from a table?
- AALTER TABLE
- BUPDATE TABLE
- CCHANGE TABLE
- DMODIFY TABLE
48In a transaction, a ROLLBACK is used to
- Aroll only the inserts and deletes of an aborted transaction into the database
- Bdiscard all the updates (including inserts, deletes, modifications) of a transaction from the database
- Croll all the updates (including inserts, deletes, modifications) of an aborted transaction into the database
- Ddiscard only the inserts and updates of a transaction from the database
49In an ER model, what is a recursive relationship type?
- AA never-ending type of relationship
- BThe relationship type where the related entities are one and the same
- CThe type of relationship between entities of one entity type
- DThe type of relationship that does not belong anywhere
50In the Entity-Relationship model, a derived attribute is one
- Athat characterizes a relationship instead of an entity
- Bthat may have multiple values simultaneously
- Cwhose value can be computed from the values of other attributes
- Dthat is composed of multiple atomic attributes
51In the Entity-Relationship model, the degree of a relationship specifies which of the following?
- AThe number of integrity constraints required to implement the relationship
- BThe cardinality ratio of the relationship
- CThe number of entities that participate in the relationship
- DThe number of attributes that characterize the relationship
52A weak entity type implies a
- Astrong relationship type
- Bweak relationship type
- Crelationship with total participation constraint
- Drelationship with partial participation constraint
53In an ER model, which of the following is true about a component attribute?
- AA component attribute is always atomic.
- BA component attribute always contains other components.
- CA component attribute can be a composite attribute.
- DComponent attributes must always be combined by an aggregation operation.
54Which of the following is true about storage for derived attributes?
- ADerived attributes must be stored.
- BDerived attributes are usually stored because storage improves retrieval performance.
- CDerived attributes are usually not stored because they can be computed.
- DDerived attributes must not be stored.
55In the Entity-Relationship model, properties that characterize entities and relationships are modeled as
- Aweak entities
- Bentity types
- Cparticipation constraints
- Dattributes
56In EER modeling, generalization is the process of generating
- Asuperclasses out of subclasses
- Battributes out of entities
- Csubclasses out of superclasses
- Dentities out of attributes
57When mapping from an ER model to a relational model, a strong entity is mapped into a
- Acolumn
- Bkey
- Crow
- Dtable
58Through normalization, data redundancy
- Acan be maximized
- Bcan be minimized but not eliminated
- Ccan be eliminated
- Dare usually left unchanged
59Which of the following problems can be caused by data redundancy in a relational schema?
I. Inefficient use of space
II. Update anomalies and possible loss of data
III. Inefficient use of processing time- AII only
- BI and III only
- CI and II only
- DI, II, and III
60Which of the following statements concerning normal forms is true?
- ASchemas that are in second normal form are considered the best.
- BEach normal form contains a state of independent properties, unrelated to other normal forms.
- CThe lower the normal form number, the better the schema design is.
- DA relation that is in second normal form is also in first normal form.
61Through normalization, update anomalies
- Acan be minimized but not eliminated
- Bcan be maximized
- Ccan be eliminated
- Dis usually left unchanged
62For a relation to be in 3NF, it should not contain _____ attribute that is transitively dependent on _____.
- Aa non-primary key, a foreign key
- Ba primary key, a non-primary key
- Ca primary key, a foreign key
- Da non-primary key, the primary key
63Consider a table with atomic attributes A, B, and C and the following functional dependencies.
A -> B
B -> C
If the primary key of this table is attribute A, then this relation satisfies which of the following normal forms?
I. First
II. Second
III. Third- AI, II and III
- BNone
- CI only
- DI and II only
64The FD X -> Y is a full dependency in a relation R, if there is _____ attribute A that can be _____ X and the dependency still holds.
- Aat least one, removed from
- Bno, removed from
- Cat least one, added to
- Dno, added to
65For a relation to be in 2NF, _____ attribute must be fully functionally dependent on _____.
- Aevery non-key, at least one key
- Bevery non-primary-key, the primary key
- Cevery non-key, every key
- Devery alternate key, the primary key
66The FD X -> Y is a partial dependency in a relation R, if there is _____ attribute A that can be _____ X and the dependency still holds.
- Aat least one, added to
- Bno, added to
- Cat least one, removed from
- Dno, removed from
67Database design typically consists of which of the following phases?
I. Conceptual design
II. Logical design
III. Physical design- AI, II, and III
- BII only
- CI only
- DII and III only
68In EER modeling, specialization is the process of generating
- Asubclasses out of superclasses
- Bsuperclasses out of subclasses
- Cattributes out of entities
- Dentities out of attributes
69In an ER model, a derived attribute is one whose values
- Athat characterizes a relationship instead of an entity
- Bthat may have multiple values simultaneously
- Cwhose value can be computed from the values of other attributes
- Dthat is composed of multiple atomic attributes
70If X -> Y, which of the following would make Y fully dependent on X?
- AY consists of multiple attributes
- BX is a single attribute
- CX consists of multiple attributes
- DY is a single attribute
71The functional dependency X -> Y is true if
- Athe value of X depends on the collective values of Y
- Ba value of Y uniquely determines a value of X
- Cthe value of Y depends on the collective values of X
- Da value of X uniquely determines a value of Y
72The term physical data independence refers to the ability to change
- Athe application programs without changing the conceptual schema
- Bthe conceptual schema without changing the application programs
- Cthe data without physically relocating the tables
- Dthe physical layout of the data without changing the external schemas, the conceptual schemas, or the application programs
73In an ER model, which of the following is true about a composite attribute?
- AA composite attribute can only be designed by users with special privileges.
- BA composite attribute can have a method attached to it.
- CA composite attribute can be broken into more basic attributes.
- DA composite attribute cannot be broken into more basic attributes.
74To improve the performance of a database,
- Anever use hash files when deciding on an appropriate indexing structure
- Bnever use buffering when transferring data between secondary storage and main memory
- Cminimize the amount of data transferred between secondary storage and main memory
- Dalways use hash files when deciding on an appropriate indexing structure
75In SQL3, inheritance is specified using which of the following keywords?
- ASUBTYPE
- BEXTENDS
- CUNDER
- DINHERIT
76In an Object-Relational model, which of the following data types are supported?
I. user-defined data types
II. ROW types
III. time-series data types- AI only
- BI, II, and III
- CI and III only
- DI and II only
77Which of the following data models currently have the predominant market share?
- Arelational
- Bobject-oriented
- Chierarchical
- Dnetwork
78A file is fully inverted if and only if
- Athe data files point to the index files
- Bthe records are stored in the descending order of the primary key
- Call the fields are indexed
- Dnone of the fields are indexed
79A shared lock on a data item represents permission to perform which of the operations, read and write, on the data item?
- ARead only
- BBoth read and write
- CWrite only
- DNeither read nor write
80In a hierarchical database, a single tree can accommodate which of the following types of binary relationships?
I. One-to-one relationships
II. One-to-many relationships
III. Many-to-many relationships- AI, II, and III
- BI only
- CNone
- DI and II only
81An index file is usually used to index ______ of the data file.
- Aall fields
- Bone field
- Cmost fields
- Dtwo fields
82In a network database, data records are represented using which of the following data structures?
- AArrays
- BMatrices
- CHash tables
- DGraphs
83In a network database, the first record of an ordered linked list that represents a one-to-many relationship is called a(n)
- Alink
- Bowner
- Cvector
- Dintermediary
84Which of the following types of databases store data in tables and represent relationships using foreign keys?
- AHierarchical databases
- BRelational databases
- CObject-oriented databases
- DNetwork databases
85In a hierarchical database, data records are represented using which of the following data structures?
- AMatrices
- BArrays
- CTrees
- DHash tables
86In Entity-Relationship (ER) modeling, an entity type that is existence-dependent on some other entity type is known as a
- Astrong entity type
- Bderived entity type
- Ccomposite entity type
- Dweak entity type
87Consider a database relation schema with three atomic attributes, A, B, and C that have the following functional dependencies.
A -> B
B -> C
If the primary key of the relation schema is attribute A, then the relation satisfies which of the following normal forms?
I. First
II. Second
III. Third- AI only
- BI, II, and III
- CNone
- DI and II only
88In the context of databases, the entity on which a weak entity depends is known as a(n)
- Abusiness rule
- Bparticipation constraint
- Cdependent entity
- Didentifying owner
89Indexing a database table _____ improve(s) query performance when the table has _____ quantities of data.
- Aalways, small
- Bnever, large
- Ccannot, large
- Dmight not, small
90A table that contains one or more repeating groups is said to be in
- AFirst Normal Form
- BSecond Normal Form
- CThird Normal Form
- DUnnormalized Form
91In SQL, the _____ clause is used to filter out rows in a SELECT statement.
- AFROM
- BGROUP BY
- CFILTER
- DWHERE
92If a transaction has a(n) _____ lock on a data item, it can _____ the item.
- Ashared, read and update
- Bexclusive, read but not update
- Cexclusive, update but not read
- Dshared, read but not update
93An integrated collection of related data constitutes a
- Adatabase system
- Bdatabase management system
- Cmetadata catalog
- Ddatabase
94In Entity-Relationship (ER) modeling, the multiplicity of a relationship is the
- Anumber of participating entity types in the relationship
- Btotal number of attributes in the entity types involved
- Cnumber of possible composite attributes that may be associated with some entity type in the relationship
- Dnumber of possible occurrences of an entity type that may relate to an associated entity type in the relationship
95Indexing a database table has the greatest effectiveness when
- Acolumn values are highly selective
- Bthe table is small
- Cthe index is large
- Dcolumns involved in equality selection are not hashed
96Which of the following statements about functional dependencies is (are) true?
I. Functional dependencies are creations of the database designer.
II. Functional dependencies are helpful in detecting potential update anomalies.
III. Functional dependencies are statements about all possible instances of a relational schema.- AI and III only
- BII and III only
- CI only
- DI, II, and III
97A data file can have
- Aat most one secondary index
- Bmore than one clustering index
- Cone primary index and one clustering index
- Dat most one primary index or one clustering index
98In database schemas, structural integrity constraints are imposed by the
- Adatabase application
- Bstructures of the database tables
- Crelationships between the database tables
- Drelational model
99In the context of databases, consider the relationship RESERVE<MEMBER,BOOK>, which indicates that a library member has reserved a book. If this relationship has a cardinality ratio of 1:N, which of the following is true?
- AMembers may reserve only a single book, but a book may be reserved by multiple members.
- BMembers may reserve only a single book, and a book may be reserved by only a single member.
- CMembers may reserve multiple books, and books may be reserved by multiple members.
- DMembers may reserve multiple books, but a book may be reserved by only a single member.
100In the SQL REVOKE command, the _____ clause can be used to specify that a granted privilege cannot be revoked if the privilege has been passed on to other users.
- APUBLIC
- BNO SHARE
- CCASCADE
- DRESTRICT
101A data file is called fully inverted if
- Athere are index entries for only some of the search key values in the file
- Bthere is an index entry for every search key value in the file
- Cthere are no secondary indexes
- Deach of its fields is associated with an index
102In a typical library database system, integrity constraints would include which of the following rules?
I. A member must be notified by e-mail when a specified book is available.
II. A library member must be prevented from borrowing a book if they have overdue books.
III. A library member must be limited to borrowing at most 3 books at a time.- AI, II, and III
- BII only
- CI and III only
- DII and III only
103Which of the following is true regarding database tables?
- ACardinality is a property of the table schema.
- BThe arity of an empty table is 0.
- CThe columns of a table must be in a specific order.
- DA value may appear multiple times in a column
104In SQL, which of the following clauses is (are) mandatory in a SELECT statement?
I. WHERE
II. GROUP BY
III. FROM- AI and III only
- BI and II only
- CNone
- DIII only
105Which of the following is the correct order of keywords for SQL SELECT statements?
- ASELECT, FROM, WHERE
- BFROM, WHERE, SELECT
- CWHERE, FROM,SELECT
- DSELECT,WHERE,FROM
106A subquery in an SQL SELECT statement is enclosed in:
- Abraces
- BCAPITAL LETTERS
- Cparenthesis
- Dbrackets
107The result of a SQL SELECT statement is a(n) ________ .
- Areport
- Bform
- Cfile
- Dtable
108Which of the following are the five built-in functions provided by SQL?
- ACOUNT, SUM, AVG, MAX, MIN
- BSUM, AVG, MIN, MAX, MULT
- CSUM, AVG, MULT, DIV, MIN
- DSUM, AVG, MIN, MAX, NAME
109In an SQL SELECT statement querying a single table, according to the SQL standard the asterisk (*) means that:
- Aall columns of the table are to be returned
- Ball records meeting the full criteria are to be returned.
- Call records with even partial criteria met are to be returned.
- DNone of the above is correct.
110The HAVING clause does which of the following?
- AActs like a WHERE clause but is used for groups rather than rows
- BActs like a WHERE clause but is used for rows rather than columns.
- CActs like a WHERE clause but is used for columns rather than groups.
- DActs EXACTLY like a WHERE clause.
111To remove duplicate rows from the results of an SQL SELECT statement, the ________ qualifier specified must be included.
- Aonly
- Bunique
- Cdistinct
- Dsingle
112When three or more AND and OR conditions are combined, it is easier to use the SQL keyword(s):
- ALIKE only.
- BIN only.
- CNOT IN only.
- DBoth IN and NOT IN.
113The SQL statement that queries or reads data from a table is ________ .
- ASELECT
- BREAD
- CQUERY
- DCREATE
114The SQL keyword BETWEEN is used:
- Afor ranges
- Bto limit the columns displayed
- Casawildcard
- DNone of the above is correct
115SQL is:
- AA programming language is (a/n)________
- BOperating system
- CData sublanguage
- DDBMS
116SQL stands for ________ .
- AStructured Query Language
- BSequential Query Language
- CStructured Question Language
- DSequential Question Language
117A view is which of the following?
- AA virtual table that can be accessed via SQL commands
- BA virtual table that cannot be accessed via SQL commands
- CA base table that can be accessed via SQL commands
- DA base table that cannot be accessed via SQL commands
118The command to eliminate a table from a database is:
- AREMOVE TABLE CUSTOMER;
- BDROP TABLE CUSTOMER;
- CDELETE TABLE CUSTOMER;
- DUPDATE TABLE CUSTOMER;
119ON UPDATE CASCADE ensures which of the following?
I. Normalization
II. Data Integrity
III. Materialized Views- AData Integrity
- Bmrrt
120Which of the following do you need to consider when you make a table in SQL?
I. Data types.
II. Primary keys.
III. Default values.- AAll of the above
- Bmrrt
121Which aggregate function is returns the number of values in a specified column?
- ACOUNT
- Bmrrt
122The SQL wildcards are ____ and ____ .
- Aasterisk (*); percent sign (%)
- Bpercent sign (%); underscore (_)
- Cunderscore(_); question mark (?)
- Dquestion mark (?); asterisk (*)
123Sequence of zero or more characters is represented as
- AString (or string of characters)
- Bmrrt
124To sort the results of a query use:
- AORDER BY
- Bmrrt
125Typically, entities have unique identifiers to allow for tracking across business processes.
- ATrue
- BFalse
126In a relationship, the association between entity types is bidirectional.
- ATrue
- BFalse
127A minimum cardinality of one makes a relationship mandatory; a minimum cardinality of zero makes a relationship optional.
- ATrue
- BFalse
128The minimum and maximum cardinalities of a weak entity are always one.
- ATrue
- BFalse
129All entity types must have a primary key, but it can be borrowed on inherited
- ATrue
- BFalse
130A common mistake in ERD diagramming is reversing the cardinality of an identifying relationship.
- ATrue
- BFalse
131A self-referencing relationship is always a 1-M relationship.
- AFalse
- BTrue
132Which are following objects of Microsoft Office Access?
I. Tables
II. Forms
III. Macros- AArithmetic
- BComparison
- CConcatenation
- DLogical
133A (An) __________________ is the set of allowable values for one or more attributes.
- ADomain
- BCoDomain
134A (An) _________________ is a row of a relation.
- ATuple
- BDomain
135What does an action allow to user QUERY-BY-EXAMPLE (QBE)?
I. Select records according to some criteria
II. Modify values of fields
III. Perform calculations on the data in tables- AI, II and III
- BI and III
- CI and II
- DII and III
136Microsoft Access follows which model for its design?
- AFlat
- BHierarchical
- CRelational
- DNetwork
137Microsoft Access. What does query display one or more predefined dialog boxes that prompt the user for the parameter value(s) (criteria)?
- AParameter
- Bsadfghj
138With SQL, how do you select all the columns from a table named "Persons"?
- ASELECT * FROM Persons
- Basdfgh
139With SQL, how do you select all the records from a table named "Persons" where the value of the column "FirstName" is "Peter"?
- ASELECT * FROM Persons WHERE FirstName=’Peter
- Basdfg
140The _______________ defines a relation consisting of the set of all tuples that are in both R and S. R and S must be union-compatible
- AProjection
- Basdfvg
141Find the SQL statement below that is equal to the following: SELECT NAME FROM CUSTOMER WHERE STATE = 'VA';
- ASELECT NAME IN CUSTOMER WHERE STATE IN ('VA');
- BSELECT NAME IN CUSTOMER WHERE STATE = 'V';
- CSELECT NAME FROM CUSTOMER WHERE STATE IN ('VA');
- DSELECT NAME WHERE CUSTOMER WHERE STATE = 'V';
142A THETA JOIN uses any of the comparison operators =, <, , >, , or
- ATrue
- BFalse
143For structured data, the schema information is mixed in with the data values, so it is sometimes referred to as self-describing data.
- ATrue
- BFalse. Semistructured.
144The _____________________ property ensures that either all the database operations in a transaction are executed or none are
- Aatomicity
- Bcdxfbgvhj
145The _____________________ property allows several users to update the same data in a controlled manner so that the result of the updates is correct.
- Aconcurrency
- Bsdfgt
146_________________ occurs when the same data is stored multiple times.
- Aredundancy
- Basdfghj
147Creating a database design that only stores each logical data item in only one place in the database is called ________________________.
- ANormalization
- Bsadcf
148The ___________________ R S keeps every tuple in the first (left) relation R; if no matching tuple is found in S, then the attributes of S in the join are filled with NULL values.
- ARIGHT JOIN
- BLEFT OUTER JOIN
- CLEFT
- DRIGHT OUTER JOIN
149If a relation schema has more than one key, each is called a ______________ key.
- Acandidate
- BFGHJ
150A ________________ conflict arises when an attribute may have different domains in two schemas, e.g., pounds vs kilograms.
- Adomain
- BCodomain
151What element do indicate square brackets [ ] ? I. required element. II. optional element. III. unique
- AII only
- BI only
- CIII only
152The command to remove rows from a table 'CUSTOMER' is
- AREMOVE FROM CUSTOMER ...
- BDROP FROM CUSTOMER ...
- CDELETE FROM CUSTOMER WHERE ...
- DUPDATE FROM CUSTOMER ...
153What are statements to define integrity constraints? I.CREATE TABLE. II. ALTER TABLE. III.CHECK
- AI and II
- BI and III
- CIII and II
- DI
154Command which is filters groups subject to some condition
- AHaving
- Bцывуыак
155Which is keyword allow to add a record using SQL in a relation?
- AINSERT
- Bывапро
156Any single character is represented as
- A_
- Bуакпен
157Which of the following is true about views being up to date?
- AViews are always up to date.
- BViews can be automatically made up to date periodically by the system.
- CViews are never up to date; there is always a lag time.
- DViews are up to date only after the synchronization operation by the user.
158 SQL query and modification commands make up a(n) ________ .
- ADDL
- BDML
- CHTML
- DXML
159The SQL wildcards are ____ and ____ .
- Aasterisk (*); percent sign (%)
- Bpercent sign (%); underscore (_)
- Cunderscore(_); question mark (?)
- Dquestion mark (?); asterisk (*)
160 _______________ operators are used to combine two text values into a single text value.
- AArithmetic
- BComparison
- CConcatenation
- DLogical
Información
- Descripción
- Test sobre Sin título, creado por Aknur Taubay el 15/04/2017.
- Autor
- Aknur Taubay
- Idioma
- English
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- 370
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