Download Database Management System Concepts and more Exams Computer Science in PDF only on Docsity!
A relationship in a database is which of the following? - - - correct answer ✅An association between entities T/F: Atomicity refers to the requirements that either all of a transaction must occur or none of it. - - - correct answer ✅True T/F: The person that has central control over a DBMS is called a DataBase Administrator (DBA) - - - correct answer ✅True T/F: An attribute takes a null value when the value of the attribute is computed to be zero. - - - correct answer ✅False T/F: The schema developed at the conceptual design phase provides a detailed overview of the enterprise. - - - correct answer ✅True One very important advantage of using a DBMS is that it offers data independence. This is defined as what? - - - correct answer ✅Application programs are insulated from changes in the way data is structured and stored. A language that is used to express database queries and updates is called: - - - correct answer ✅A data manipulation language
A language in which a user specifies a database schema is called: - -
- correct answer ✅A data definition language Typical functions of a database administrator would include which of the following? - - - correct answer ✅Storage structure and access- method definition Schema definition. Security and access rights definitions. T/F: The DDL interpreter of the query processor is responsible for query optimization. - - - correct answer ✅False T/F: It is desirable for all users to see the entire logical model. - - - correct answer ✅False Which of the following are components of the storage manager? - -
- correct answer ✅Buffer Manager Authorization and integrity manager Transaction manager File Manager
We must protect the data from inconsistent changes made by different users accessing the data concurrently. We need special programs to answer each question a user may want to ask about the data. We must ensure the data is restored to a consistent state if the system cashes while changes are being made. T/F: It is not possible for several attributes to have the same domain, we require they be unique. - - - correct answer ✅False A ___________________ is a minimal superkey. - - - correct answer ✅Candidate key T/F: Relational Algebra is a non-procedural query language. - - - correct answer ✅False T/F: For each attribute, there is a set of permitted values called the domain or the value set. - - - correct answer ✅True The logical design of the database is called which of the following? -
- correct answer ✅Database schema
T/F: The schema of a relation changes when tuples are added to the database. - - - correct answer ✅False T/F: The order of how a tuple appears in a relations is extremely important as that is what determines the primary key. - - - correct answer ✅False An instance of a relation is which of the following: - - - correct answer ✅A set of tuples, also called records, in which each tuple has the same number of fields as the relation schema. A domain is _____________________ if the elements of the domain are considered to be indivisible units. - - - correct answer ✅Atomic How many tuples are there in a row of a table with a column header with 3 attributes? - - - correct answer ✅a 3-tuple Superkey: - - - correct answer ✅a set of one or more attributes that allow us to identify an entity in the entity set Candidate key: - - - correct answer ✅a superkey that contains no extraneous attributes
T/F: A relation schema consists of a list of attributes and their corresponding domains. - - - correct answer ✅True One domain value that is a member of any possible domain is what? - - - correct answer ✅Null Selection: - - - correct answer ✅Return rows of the input relation that satisfy the predicate Projection: - - - correct answer ✅Output specified attributes from all rows of the input relation. Remove duplicate tuples from the output. Natural join: - - - correct answer ✅Output pairs of rows from the two input relations that have the same value on all attributes that have the same name. Cartesian product: - - - correct answer ✅Output all pairs of rows from the two input relations (regardless of whether or not they have the same values on common attributes) Union: - - - correct answer ✅Output the union of tuples from the two input relations.
T/F: A foreign key is the primary key of another relation schema. - -
- correct answer ✅True Which of the following are set operations within SQL? - - - correct answer ✅Union Intersect Except Which of the following is information the DDL features of SQL can specify about a relation? - - - correct answer ✅The schema about each relation. The integrity constraints A set of indices to be maintained for each relation The JDBC connector The _________________ command is used to insert data into a relation. - - - correct answer ✅Insert Which of the following are aggregate functions? - - - correct answer ✅Avg Min Count
Match the domain type to its description. Char(n): - - - correct answer ✅a fixed-length character string Match the domain type to its description. Varchar(n): - - - correct answer ✅a variable length character string Match the domain type to its description. Int: - - - correct answer ✅integer Match the domain type to its description. Smallint: - - - correct answer ✅small integer Match the domain type to its description. Numeric: - - - correct answer ✅a fixed-point number with user specified precision Match the domain type to its description. Real, double-precision: - - - correct answer ✅floating-point and double-precision floating point numbers Match the result of handling an unknown value in the "and" boolean operation.
True and unknown: - - - correct answer ✅unknown Match the result of handling an unknown value in the "and" boolean operation. False and unknown: - - - correct answer ✅false T/F: When using the GROUP BY clause, you cannot have a column in the select clause that is not in the grouping-list. - - - correct answer ✅False SELECT __________ forces the elimination of duplicates. - - - correct answer ✅Distinct In SQL, we can using pattern matching to match strings. The pattern '__% Cubs' does which of the following (note, there are 2 underline characters before the %): - - - correct answer ✅Matches any string of at least 2 characters followed by a space and Cubs. T/F: An identifer that is used to rename a relation is referred to as a correlation name in the SQL standard. - - - correct answer ✅True T/F: We can disallow null values by specifying NOT NULL as a part of the field definition. This MUST be specified when declaring the primary key. - - - correct answer ✅False
T/F: We create a table in SQL using the insert table command. - - - correct answer ✅False Which of the following is true about SQL? - - - correct answer ✅SQL is both a Data Manipulation Language (DML) and a Data Definition Language (DDL). T/F: We remove a relation from an SQL database using the drop table command. - - - correct answer ✅True T/F: The natural join operation operates on two relations and produces a single relation as the result. - - - correct answer ✅True T/F: SOME and ANY mean the same thing - - - correct answer ✅True T/F: A transaction is a single operation that performs multiple logical functions within a database. - - - correct answer ✅False Views are considered updatable if which of the following conditions are satisfied: - - - correct answer ✅The from clause only had one database relation
The select clause contains only attribute names of the relation and does not have an expressions, aggregates or distinct specification. Any attribute not listed in the select clause can be set to null. T/F: The SQL phrase "ON DELETE CASCADE" is associated with referential integrity as it applies to the WHERE clause. - - - correct answer ✅False Which of the following are data types the SQL standard supports? -
- correct answer ✅Date Time Timestamp Right outer join: - - - correct answer ✅tuples from the right hand side that don't match the left are padded with nulls Left outer join: - - - correct answer ✅tuples from the left hand side that don't match the right are padded with nulls Full outer join: - - - correct answer ✅both left and right are extended and filled with nulls for non-existent values
To distinguish normal joins from outer joins, normal joins are called which of the following? - - - correct answer ✅Inner joins T/F: The participation of an entity set E in a relationship set R is said to be total if every entity E participates in at least one relationship in R. - - - correct answer ✅True T/F: The discriminator of a weak entity set is the combination of the primary key from the identifying realtionship set and enough attributes to distinguish the weak entity set. - - - correct answer ✅False Which integrity constraint is used to establish and enforce referential integrity? - - - correct answer ✅Foreign key constraint Entity: - - - correct answer ✅a thing or object in the real world that is distinguishable from all other objects Entity set: - - - correct answer ✅a set of objects of the same type that share the same properties Attribute: - - - correct answer ✅descriptive properties possessed by each member of an entity set
Value: - - - correct answer ✅assigned to each attribute with an entity ___________________________ constraints ensure that a value that appears in one relation for a given set of attributes also appears for a certain set of attributes in another relation. - - - correct answer ✅Referential integrity T/F: It is required that the primary key of an entity set be used as an attribute of another entity set when that entity set is in total participation of a relationship set. - - - correct answer ✅False Date is an example of which type of attribute. - - - correct answer ✅Composite attribute. Match the component of an E-R diagram to its description. Rectangles: - - - correct answer ✅entity sets Match the component of an E-R diagram to its description. Items within the rectangles: - - - correct answer ✅attributes Match the component of an E-R diagram to its description. Diamonds: - - - correct answer ✅relationship sets
Composite attributes: - - - correct answer ✅Attributes that are divided into other attributes. Single-valued attribute: - - - correct answer ✅Attributes that have a single value for a particular entity. Multi-valued attribute: - - - correct answer ✅Attributes that have a set of values for a particular entity. Derived attribute: - - - correct answer ✅An attribute whose value is computed from the values of other attributes. ___________________ specify the set of possible values that may be associated with an attribute. - - - correct answer ✅Domain constraints The cardinality of a database relation is ______________________.
- correct answer ✅The number of relationships in which the entity is involved A faculty member is a person; a student is a person. These are two examples of ________________________. More than one answer may apply. - - - correct answer ✅generalization the IS-A relationship
Relationship: - - - correct answer ✅An association among several entities. Relationship set: - - - correct answer ✅A set of associations among several entities of the same type. Participation: - - - correct answer ✅When an entity set is a part of a relationship set. Relationship instance: - - - correct answer ✅In an E-R schema, this represents an association between the named entities in the real world enterprise being modeled. One-to-one: - - - correct answer ✅An entity in A is associated with at most one entity in B, and an entity in B is associated with at most one entity in A. Match the key and participation constraint to its appropriate description. One-to-many: - - - correct answer ✅An entity in A is associated with any number of entities in B. An entity in B is associated with at most one entity in A.
