What does the “x” operator do in relational algebra

DBMS /RDBMS MCQs

• State true or false: SQL specifies a way of mentioning functional dependencies
• State true or false: Most current database systems do not support constraints on materialized view
• Multi valued dependencies are also called as __________
• Functional dependencies are sometimes referred to as ________
• The _______ is a set of all functional and multi values dependencies implied by a set of functional dependencies
• State true or false: If a relational schema is in _______ NF and A is a subset of R and B is also a subset of R then it is that A is a superkey is a trivial multi values dependency
• Which of the following normal forms does not exist
• Choose the correct statement regarding superkeys
• What is an Instance of a Database
• What is a foreign key
• What action does ⋈ operator perform in relational algebra
• What does the “x” operator do in relational algebra
• An attribute is a __________ in a relation
• What is the method of specifying a primary key in a schema description?
• Two Statements
• Choose the option that correctly explains in words, the function of the following relational algebra expression
• State true or false: If a relation consists of a foreign key, then it is called a referenced relation of the foreign key dependency
• Which of the following is not a feature of a good relational design
• The dependency rules specified by the database designer are known as _______
• If the decomposition is unable to represent certain important facts about the relation, then such a decomposition is called as
• If the decomposition is able to represent all the facts about the relation then such a decomposition is called as
• A domain whose elements are indivisible is called as ______
• If all the domains are atomic then the relational schema is in ________ normal form
• State true or false: Composite attributes have non-atomic domains
• State true or false: Redundancy is desired in a relational schema
• An instance of a relation that satisfies all real world constraints is known as
• If K → R then K is said to be the _______ of R
• X → Y holds on a schema k(K) if
• X→ Y is trivial if
• Which of the following is not a condition for X→ Y in Boyce codd normal form
• Which of the following is used to express database consistency
• Which of the following is not a condition for the third normal form in the case of X→Y
• F+ is called as the ________ of F
• State true or false: A functional dependency must first satisfy the second normal form to satisfy the third normal form
• State true or false: The fourth normal form does not exist and it is instead called as the BCNF
• A functional dependency f on R is _______ by a set of functional dependencies F on r if every instance of r(R) that satisfies f also satisfies F
• If F is a set of functional dependencies, then the closure of F is denoted by
• If a functional dependency is reflexive, B is a subset of A and A is the set of attributes, then
• State true or false: Armstrong’s axioms allow us to generate all F+ for any given F
• Armstrong axioms are called sound because
• State true or false: Functional dependencies are transitive
• If A→B, A→ C then which of the following is true
• If B is an attribute and A→B, Then B is said to be ________ by a
• We say that a decomposition having the property F’+ = F+ is a __________ decomposition
• A _________ Fc for F is a set of dependencies such that F logically implies all dependencies in Fc, and Fc logically implies all dependencies in F
• What does the BCNF decomposition algorithm do
• The 3NF decomposition algorithm is also called as _______
• Which of the following is desirable in a database design with functional dependencies
• Which of the following is not a process of generating a good relational schema
• What is unique role assumption
• The process of making a normalized schema unnormalized is called as _________
• State true or false: Crosstabs are not desirable in a database design
• The data that have a time interval associated with them during which they are valid are called as ________
• The value of the data at a particular time is called as
• Functional dependencies that have a time associated with them during which they are valid are called as________
• State true or false: Overlapping time intervals cannot be prevented
• Which of the following is the time of temporal data that record when a fact was recorded in a database
• To specify the foreign keys in relations referencing temporal data we need to specify _______
• A relational database consists of a collection of
• A ________ in a table represents a relationship among a set of values
• The term _______ is used to refer to a row
• The term attribute refers to a ___________ of a table
• For each attribute of a relation, there is a set of permitted values, called the ________ of that attribute
• Database __________ which is the logical design of the database, and the database _______ which is a snapshot of the data in the database at a given instant in time
• Course(course_id,sec_id,semester)
• Department (dept name, building, budget) and Employee (employee_id , name, dept name,salary)
• A domain is atomic if elements of the domain are considered to be ____________ units
• The tuples of the relations can be of ________ order
• The ______ is the one in which the primary key of one relation is used as a normal attribute in another relation
• Using which language can a user request information from a database
• Student(ID, name, dept name, tot_cred)
• Which one of the following is a procedural language
• The_____ operation allows the combining of two relations by merging pairs o tuples, one from each relation, into a single tuple
• The result which operation contains all pairs of tuples from the two relations, regardless of whether their attribute values match
• The _______operation performs a set union of two “similarly structured” tables
• The most commonly used operation in relational algebra for projecting a set of tuple from a relation is
• The _______ operator takes the results of two queries and returns only rows that appear in both result sets
• A ________ is a pictorial depiction of the schema of a database that shows the relations in the database, their attributes, and primary keys and foreign keys
• The _________ provides a set of operations that take one or more relations as input and return a relation as an output

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• DBMS /RDBMS MCQs

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