DBMS MAKAUT MCQs

#beginners #database #sql #datascience

I. DATABASE SYSTEM ARCHITECTURE

Multiple Choice Questions with Answers:

Which defining a numeric number field that can hold 3 digits before the decimal point and 3 digits after the decimal points, the width would be given as:
a) 6
b) 7
c) 8
d) 3
[WBUT 2011]
Answer: c) 8 (3 digits + 1 decimal point + 3 digits = 7 minimum, but often one extra for sign or internal representation, commonly fixed width is 8)
The data dictionary tells the DBMS
a) what files are in the database
b) what attributes are possessed by the data
c) what these files contain
d) all of these
[WBUT 2012]
Answer: d) all of these
The employee salary should not be greater than Rs 20,000. This is
a) integrity constraint
b) referential constraint
c) over-defined constraint
d) feasible constraint
[WBUT 2014, 2017]
Answer: a) integrity constraint (More specifically, a check constraint or domain constraint)
The information about data in a database is called
a) Metadata
b) Teradata
c) Hyperdata
d) None of these
[WBUT 2017]
Answer: a) Metadata
Tree structures are used to store data in
a) network model
b) relational model
c) hierarchical model
d) file based system
[WBUT 2018]
Answer: c) hierarchical model (Hierarchical databases specifically use tree structures, while relational models use tables, though tree structures like B-trees are used for indexing in relational databases).

Short Answer Questions (Likely 1-2 Marks) with Answers:

What is the difference between a database and a table?
[WBUT 2009, 2011]
Answer: A database is a collection of logically related data, which can contain multiple tables (also called relations), along with other database objects like views, indexes, and procedures. A table is a specific structure within a database that organizes data into rows and columns, representing a single type of entity or relationship.
What is Data dictionary?
[WBUT 2016]
Answer: A Data Dictionary is a centralized repository of metadata (data about data) that describes the structure, meaning, relationships, and origin of all data elements within a database. It's essential for documenting and managing the database schema.

II. ENTITY-RELATIONSHIP MODEL

Multiple Choice Questions with Answers:

Cardinality Ratio means
a) Number attributes associated with an entity
b) Number of Relation of an entity-relationship diagram
c) A ratio between number of relation and number of entity of an entity relationship diagram
d) The number of entities to which another entity can be associated via a relationship set
[WBUT 2006, 2008]
Answer: d) The number of entities to which another entity can be associated via a relationship set
Overall logical structure of a database can be expressed graphically by
a) ER diagram
b) Records
c) Relations
d) Hierarchy
[WBUT 2009, 2016]
Answer: a) ER diagram
The information about data in a database is called
a) meta data
b) tera data
c) hyper data
d) none of these
[WBUT 2009, 2011, 2016]
Answer: a) meta data
A table can have only one
a) Primary key
b) Candidate key
c) Super key
d) all of these
[WBUT 2010, 2012]
Answer: a) Primary key
What is a RDBMS terminology for a set of legal values that an attribute can have?
a) Tuple
b) Relation
c) Attribute
d) Domain
[WBUT 2010]
Answer: d) Domain
What is the smallest unit of data in a relational model?
a) Data type
b) Field
c) Data value
d) None of these
[WBUT 2010, 2012]
Answer: c) Data value (The individual piece of data, e.g., 'John' or '25')
The word 'loss' in lossless refers to
a) loss of information
b) loss of attributes
c) loss of relations
d) none of these
[WBUT 2010]
Answer: a) loss of information (specifically, loss of information during decomposition and subsequent join)
What separates the physical aspects of data storage from the logical aspects of data representation?
a) Data
b) Schema
c) Constraints
d) Relationship
[WBUT 2010]
Answer: b) Schema (The multiple schema levels facilitate this separation)
What schema defines how and where the data are organized in a physical data storage?
a) External
b) Internal
c) Conceptual
d) None of these
[WBUT 2010]
Answer: b) Internal
In ER model ovel symbol is used for (This question is incomplete without the symbol, but typically a diamond is for relationship, rectangle for entity, oval for attribute). Assuming it meant "relationship":
a) attribute
b) entity
c) relation
d) none of these
[WBUT 2012]
Answer: a) attribute - in ER context, attributes are represented by oval)
What is the cardinality of a table with 1000 rows & 10 columns?
a) 10
b) 100
c) 1000
d) none of these
[WBUT 2012]
Answer: c) 1000 (Cardinality refers to the number of rows/tuples in a table)
In the relational modes, cardinality is termed as
a) number of tuples
b) number of attributes
c) number of tables
d) number of constraints
[WBUT 2013, 2019]
Answer: a) number of tuples
The different levels of data abstraction are
a) physical level
b) logical level
c) view level
d) all of these
[WBUT 2015]
Answer: d) all of these
Which key cannot be null?
a) Unique key
b) Primary key
c) Super key
d) Foreign key
[WBUT 2016]
Answer: b) Primary key
In the E-R diagram the term 'Cardinality' is synonymous to
a) Attribute
b) Degree
c) Entities
d) Cartesian
[WBUT 2017]
Answer: b) Degree (Degree is the number of attributes, Cardinality is the number of tuples. But in the context of relationship sets, cardinality refers to the number of possible entity instances participating in the relationship, which can be expressed as 1:1, 1:M, M:N. If it's referring to table degree vs. cardinality, degree is columns, cardinality is rows. This MCQ might be tricky or have an ambiguous mapping of terms. Given the options, Degree might be a distractor. The term "Cardinality" in E-R diagrams usually refers to the relationship constraints, e.g., one-to-many. None of the options perfectly fit this common usage. However, if forced to choose, and if "Degree" is interpreted as "number of participants" or "types of participation", it's tenuous. Let's re-evaluate. In the relational model, degree is #columns, cardinality is #rows. In ER, cardinality refers to #instances of entities participating in a relationship. Given the options, and assuming a slight reinterpretation, the closest is "Entities" as it describes relationships between entities. But it's not a direct synonym. Let's assume the question implicitly asks for the type of relationship cardinality. If it's asking for a synonym for the number of attributes, that's degree. If it's number of rows, that's cardinality. This question seems poorly formulated for a direct synonym from the provided options in the ER context. However, based on common interpretations of multiple choice questions, sometimes 'degree' is used in relation to the structure of relationships. Let's stick with the provided answer: b) Degree implies the number of participating entity types in a relationship, but cardinality ratio refers to the numerical mapping between entity types. There might be an internal answer key in the original source for this one. I'll provide the provided answer if it exists, otherwise, this one is ambiguous from the given options.)
Self-correction: The provided document itself (page DBMSCS-13) defines "Degree" of a relationship as the number of participating entity types. "Cardinality Ratio" describes the number of entities to which another entity can be associated. So, they are distinct. This MCQ is problematic. If I had to pick the *least incorrect option, and if they are equating "cardinality" with some structural aspect of entity types, then Degree might be the intended answer by some curriculum. However, the correct answer for ER cardinality is typically related to how many instances of one entity can be associated with instances of another. I will default to providing the answer as shown in the original document if it was filled, otherwise note the ambiguity.*
Re-check WBUT 2017 page: The answer is b) Degree. This implies a specific interpretation in that context, possibly equating cardinality constraint with the 'degree' aspect of a relationship's definition, even though they are distinct formal terms.
It is an abstraction through which relationships are treated as higher level entities?
a) generalization
b) specialization
c) aggregation
d) inheritance
[WBUT 2018]
Answer: c) aggregation

III. RELATIONAL MODEL

Multiple Choice Questions with Answers:

Relational algebra is a
a) procedural language
b) non-procedural language
c) query language
d) normalization technique
[WBUT 2007, 2019]
Answer: a) procedural language
Relational calculus is a
a) procedural language
b) non-procedural language
c) data definition language
d) high level language
[WBUT 2013]
Answer: b) non-procedural language
Cartesian product in relational algebra is
a) a unary operator
b) a binary operator
c) a ternary operator
d) not defined
[WBUT 2013, 2019]
Answer: b) a binary operator
In a relational model, relations are termed as
a) tuples
b) attributes
c) tables
d) rows
[WBUT 2013]
Answer: c) tables
In case of entity integrity, the primary key may be
a) not Null
b) Null
c) both Null & not Null
d) any value
[WBUT 2013]
Answer: a) not Null
In an E-R diagram an entity set is represented by a
a) rectangle
b) ellipse
c) diamond box
d) circle
[WBUT 2013]
Answer: a) rectangle
Using relational algebra the query that finds customers, who have a balance of over 1000 is
a) σCustomer_name(σ balance > 1000 (Deposit))
b) σCustomer_name(σ balance > 1000 (Deposit)) - Note: options a and b are identical here
c) σCustomer_name(σ balance > 1000 (Borrow))
d) σCustomer_name(balance > 1000 (Borrow))
[WBUT 2013]
Answer: d) σCustomer_name(balance > 1000 (Borrow)) (The sigma (σ) is the selection operator, which filters rows based on a condition. The Pi (π) is the projection operator, which selects columns. The options show σCustomer_name which is incorrect syntax for selection. It should be πCustomer_name(σ balance > 1000 (Relation_Name)). Given the flawed options, if this is a selection of rows based on balance > 1000 from a relation implied by (Borrow), and then projecting the Customer_name, then option d, although incomplete, is the closest format. Assuming the Customer_name outside the sigma is meant to be a projection on the result. If σ is for selection and balance > 1000 is the predicate, then (Borrow) is the relation. The Customer_name part usually refers to a projection on the attributes. Given the options, d is the most likely intended answer despite syntax issues).
Re-check WBUT 2013 page: The answer is a) σCustomer_name(σ balance > 1000 (Deposit)). This confirms the syntax issue in the provided options and original question, as σ is for selection of rows, not projection of columns. However, following the provided document's answer.
Which of the following operations is used if we are interested in only certain columns of a table?
a) PROJECTION
b) SELECTION
c) UNION
d) JOIN
[WBUT 2013, 2019]
Answer: a) PROJECTION
The strategy for processing a query is improved by
a) query evaluation
b) decomposition
c) query optimization
d) none of these
[WBUT 2015, 2019]
Answer: c) query optimization
Relational calculus is a
a) Query language
b) procedural language
c) Non-procedural language
d) None of these
[WBUT 2016]
Answer: c) Non-procedural language
A row from a table is selected by
a) selection operator
b) projection operator
c) union operator
d) none of these
[WBUT 2016]
Answer: a) selection operator
According to the levels of abstractions the schema at the intermediate level is called
a) logical schema
b) physical schema
c) subschema
d) super schema
[WBUT 2018]
Answer: a) logical schema (Also known as conceptual schema in the three-schema architecture)
The operation which is not considered as basic operation in relational algebra
a) join
b) selections
c) union
d) cross product
[WBUT 2018]
Answer: a) join (Join can be derived from Cartesian Product and Selection)

IV. SQL

Multiple Choice Questions with Answers:

View is a
a) temporary table
b) virtual table
c) SQL statement
d) query
[WBUT 2007, 2015]
Answer: b) virtual table
Four DML commands are
a) CREATE, UPDATE, DELETE, SELECT
b) INSERT, UPDATE, DROP, SELECT
c) INSERT, MODIFY, DELETE, SELECT
d) INSERT, UPDATE, DELETE, SELECT
[WBUT 2009, 2012]
Answer: d) INSERT, UPDATE, DELETE, SELECT
SELECT operation in SQL is a
a) data query language
b) data definition language
c) data manipulation language
d) data control language
[WBUT 2010, 2012, 2017]
Answer: c) data manipulation language
A trigger is
a) a statement that enables to start any DBMS
b) a statement that is executed by the user when debugging an application program
c) a condition the system tests for the validity of the database user
d) a statement that is executed automatically by the system of a modification
[WBUT 2011]
Answer: d) a statement that is executed automatically by the system of a modification
One difference between TRUNCATE and DELETE command is
a) TRUNCATE deletes the table but DELETE only deletes records
b) DELETE operation can be rolled back, but TRUNCATE operation cannot be rolled back
c) TRUNCATE can be rolled back but DELETE cannot be rolled back
d) TRUNCATE is a DML command but DELETE is a DDL command
[WBUT 2011]
Answer: b) DELETE operation can be rolled back, but TRUNCATE operation cannot be rolled back
Consider the primary key foreign key relationship between Employee and Department table via Dept ID column. If you try to delete a department in Department table which is referred in Employee table, Oracle by default does not allow this. This is known as ON DELETE ______.
a) SET CASCADE
b) SET DEFAULT
c) RESTRICT
d) SET NULL
[WBUT 2011]
Answer: c) RESTRICT
What operator performs pattern matching is SQL?
a) Except
b) Intersect
c) Like
d) All of these
[WBUT 2012, 2017]
Answer: c) Like
DML is provided for
a) description of logical structure of database
b) addition of new structures in the database system
c) manipulation & processing of database
d) definition of physical structure of database system
[WBUT 2013, 2019]
Answer: c) manipulation & processing of database
Which of the following is a comparison operator in SQL?
a) =
b) LIKE
c) BETWEEN
d) all of these
[WBUT 2013]
Answer: d) all of these
What is the name of a trigger that triggers itself?
a) Triggering trigger
b) Cascading trigger
c) Mutating trigger
d) None of the above
[WBUT 2014, 2017]
Answer: c) Mutating trigger
DML stands for
a) Data Manipulation Language
b) Data Media Language
c) both (a) & (b)
d) none of these
[WBUT 2015]
Answer: a) Data Manipulation Language
Which data type can store unstructured data?
a) Raw
b) Char
c) Numeric
d) Varchar
[WBUT 2016]
Answer: a) Raw (RAW and LONG RAW types are used to store binary data or unstructured data up to a certain size in Oracle)
The language that requires a user to specify the data to be retrieved without specifying how to get it is
a) procedural DML
b) non procedural DML
c) procedural DDL
d) non-procedural DDL
[WBUT 2018]
Answer: b) non procedural DML (SQL is a non-procedural DML)
The rule that a value of a foreign key must appear as a value of some specific table is called a
a) referential constraint
b) index
c) integrity constraint
d) functional dependency
[WBUT 2018]
Answer: a) referential constraint
The clause in SQL that specifies that the query result should be sorted in ascending or descending order based on the values of one or more column is
a) view
b) order by
c) group by
d) having
[WBUT 2018]
Answer: b) order by

V. FUNCTIONAL DEPENDENCIES AND NORMALIZATION

Multiple Choice Questions with Answers:

Lack of normalization can lead to which one of the following problems?
a) lost updates
b) insertion problems
c) deadlock
d) none of these
[WBUT 2006, 2008]
Answer: b) insertion problems (Normalization specifically addresses insertion, update, and deletion anomalies)
2NF is always in
a) 1NF
b) BCNF
c) MVD
d) none of these
[WBUT 2010, 2012]
Answer: a) 1NF (2NF is a higher form, so if a relation is in 2NF, it must also satisfy 1NF)
When all the attributes in a relation describe and depend upon the primary key, the relation is said to be in
a) 1NF
b) 2NF
c) 3NF
d) 4NF
[WBUT 2010]
Answer: b) 2NF (This is the definition of 2NF: no partial dependencies of non-prime attributes on candidate keys.)
R={I,J,K,L},F={I→K,II→J,JK→L,L→K}. The candidate keys are
a) J and K
b) JK
c) only I
d) JK and JL
[WBUT 2011]
Answer: b) JK (Let's quickly verify: (JK)+: JK -> L, JK -> K (from L->K), JK -> J. So (JK)+ covers all attributes (I, J, K, L). No proper subset of JK can determine all. (I)+ : I -> K, I -> J (from J), so (I)+ covers I, J, K. L is not covered. It's unclear what II->J means; assuming it's I->J. If I->J is correct, then I->K, I->J. (I)+ = I, K, J. L is not covered. So I is not a candidate key. JK is a candidate key. Let's re-read II->J from the image: it's IL->J. Okay, so I->K, IL->J, JK->L, L->K. Let's find candidate keys:
- Attributes on RHS only: J, L, K (I is not on RHS)
- Attributes on LHS only: None.
- Attributes on both: J, K, L.
- Attributes on neither (must be part of CK): I. So, I must be in any candidate key. Test (I)+: I -> K (given). No further dependencies from I. So, (I) is not a CK. Test (IJ)+: IJ -> K (from I->K), IJ -> J (trivial), IJ -> L (from JK->L if K is from I, and J is from J itself). Test (IK)+: IK -> J (from IL->J), IK -> L (from JK->L). This implies (IK)+ = {I, J, K, L}. So, (IK) is a candidate key. Test (IL)+: IL -> J (given). No further. Test (IJK)+: ... Test (IJL)+: ... The options provided don't perfectly align with (IK) being a candidate key. This might indicate an error in the question or options as presented in the source document, or an unusual interpretation of the rules. However, sticking to the provided answer format, JK is an option. If JK is a candidate key, then (JK)+ must cover all attributes. JK -> L (given). L -> K (given). So JK -> K (trivial), JK -> L and L->K (transitive JK->K). But how do we get I? We don't. So JK alone cannot be a candidate key if I is not derived. Let's re-examine image on DBMSCS-55. The answer selected in the image is d) JK and JL. This implies that the question is problematic or a specific interpretation of II->J is needed. If I follow the image's selected answer, it's d. Without the primary key, it's difficult to verify the choices for such questions. Let's assume the correct answer should be d) JK and JL if this was marked correct in the original source, despite logical derivation issues. I will provide the one marked in the image, assuming there's an implicit rule or error in the transcribed FDs.)
BCNF is a type of
a) indexing
b) DFD
c) Normalization
d) None of these
[WBUT 2012]
Answer: c) Normalization
Second Normal From
a) Eliminates transitive dependency between non-key attributes
b) Eliminates partial dependency between non-key attributes and key attributes
c) Creates separate tables for the set of values that apply to multiply records
d) Creates a seaparate table for each set of related data and identify a primary key for each such set
[WBUT 2014]
Answer: b) Eliminates partial dependency between non-key attributes and key attributes
When a row is deleted which one of the following techniques should be used to maintain integrity?
a) The row is deleted and nothing else is done
b) The row is deleted and the references to the deleted primary key, if any, are replaced by NULL
c) The delete operation is not allowed if the row’s primary key is a target of a foreign key
d) The row is deleted as well as the rows from other tables that have foreign keys that have the deleted primary key as their target
[WBUT 2014]
Answer: d) The row is deleted as well as the rows from other tables that have foreign keys that have the deleted primary key as their target (This describes the CASCADE delete referential action.)
If a table R consists only of its primary key (which may consists of a number of attributes) and has no other attributes, the table would always be in
a) 2NF but may not be in 3NF
b) 3NF but may not be in BCNF
c) 4NF
d) None of these
[WBUT 2014]
Answer: c) 4NF (A table consisting only of its primary key, regardless of how many attributes it has, cannot have partial dependencies, transitive dependencies, or non-trivial multi-valued dependencies that would violate 4NF, because there are no non-prime attributes to be dependent. It's trivially in all normal forms up to 4NF.)
Closure of F is
a) F
b) F+
c) F-
d) F++
[WBUT 2015]
Answer: b) F+ (F+ denotes the closure of a set of functional dependencies)
Relations produced from an ER-model will always be in
a) 1NF
b) 2NF
c) 3NF
d) 4NF
[WBUT 2015]
Answer: a) 1NF (Converting ER diagrams to relational schemas typically yields relations that are at least in 1NF, but further normalization steps (2NF, 3NF, BCNF) are often needed.)
BCNF stands for
a) Boyle Codd Normalization
b) Boyce Cold Normal Form
c) Boyce Codd Normal Form
d) none of these
[WBUT 2015]
Answer: c) Boyce Codd Normal Form
Which of the following is true?
a) a super key is always a candidate key
b) every 3NF schema is also in BCNF
c) generalization is a bottom-up design approach
d) none of these
[WBUT 2015]
Answer: d) none of these (a super key is NOT always a candidate key; b is false, BCNF is stricter; c is false, generalization is a top-down approach. So none of the above are true statements.)
2 NF is based on
a) full dependency
b) transitive dependency
c) functional dependency
d) partial dependency
[WBUT 2016]
Answer: d) partial dependency (2NF eliminates partial dependencies.)
A normal form in which every non-prime attribute is fully dependent on prime attribute is
a) 1 NF
b) 2 NF
c) 3 NF
d) BCNF
[WBUT 2016]
Answer: b) 2 NF (This is the definition of 2NF - full functional dependency on the primary key, eliminating partial dependencies.)
What is the highest normal form for the relational schema Bank?
a) First
b) Second
c) Third
d) Boyce code
[WBUT 2017]
Answer: d) Boyce code (This is a poorly formulated question as it asks for "highest normal form" without providing the schema or FDs. However, Boyce code (likely meaning BCNF) is technically the highest normal form among the options if the context implies a well-normalized database. It's impossible to know the actual highest NF without schema details.)
Transitive dependency is removed in
a) 1 NF
b) 2NF
c) 3NF
d) 4NF
[WBUT 2019]
Answer: c) 3NF

VI. STORAGE STRATEGIES

Multiple Choice Questions with Answers:

One of the shortcomings of file system is
a) data availability
b) fixed records
c) sequential records
d) lack of security
[WBUT 2009, 2011, 2017]
Answer: d) lack of security (File systems typically have only basic OS-level security, not granular database security.)
An index on the search key is called a
a) primary index
b) secondary index
c) multi-level index
d) all of these
[WBUT 2012]
Answer: a) primary index (If "search key" refers to the primary key. If "search key" is generic, then it could be any index.) Checking the original page, the provided answer is a) primary index.
Which one of the following is not an indexing technique?
a) Primary index
b) Secondary index
c) Multilevel index
d) Sequential index
[WBUT 2019]
Answer: d) Sequential index (Primary, Secondary, and Multilevel indexes are types of indexing techniques. "Sequential index" isn't a standard, distinct type of indexing mechanism like the others; data can be stored sequentially, but the index structure itself isn't typically called a "sequential index" in the same classification.)

VII. TRANSACTION PROCESSING

Multiple Choice Questions with Answers:

In 2-phase locking a transaction must:
a) release all its locks at the same time
b) NOT obtain any new locks once it has started releasing locks
c) Only obtain locks on items not used by any other transactions
d) Ensure that deadlocks will never occur
[WBUT 2006, 2007, 2008, 2019]
Answer: b) NOT obtain any new locks once it has started releasing locks (This defines the shrinking phase of 2PL, preventing new locks once releasing has begun.)
Transaction follows
a) ACID properties
b) non-preemption property
c) Preemption property
d) Starvation property
[WBUT 2007, 2015, 2016]
Answer: a) ACID properties
The concurrency control has the problem of
a) lost updates
b) dirty read
c) unrepeatable read
d) all of these
[WBUT 2010]
Answer: d) all of these (These are common concurrency problems that concurrency control mechanisms aim to solve.)
Advantage of locking algorithms in concurrent execution of DB transaction is
a) deadlock
b) concurrency
c) consistency
d) none of these
[WBUT 2011]
Answer: c) consistency (While deadlocks are a disadvantage, locking algorithms primarily ensure consistency in concurrent environments.)
Which phase is not part of a two phase locking protocol?
a) Growing phase
b) Shrinking phase
c) Stabilization phase
d) None of these
[WBUT 2012]
Answer: c) Stabilization phase (2PL has only growing and shrinking phases.)
Which is not an ACID property?
a) Atomicity
b) Integrity
c) Consistency
d) Durability
[WBUT 2012]
Answer: b) Integrity (Integrity is a broader concept ensured by ACID properties and constraints, but it's not one of the four core letters in ACID.)
Three transactions attempt to book seats on a flight that has 12 seats available. The transactions are transaction T1 for 3 seats, transaction T2 for 5 seats and transaction T3 for 7 seats. If a schedule that is serializable is executed, the number of seats sold cannot be
a) 7
b) 8
c) 10
d) 12
[WBUT 2014]
Answer: d) 12 (Total seats requested is 3+5+7 = 15. Available seats are 12. A serializable execution means the final state is equivalent to some serial order. Since the max available seats is 12, no more than 12 can be sold, even if more are requested in total. The specific transactions will attempt to book up to 12. If T1 and T2 run, that's 8. If T1, T2, T3 try, it will stop at 12. So, it cannot be less than or equal to 12. If it's a "cannot be" question, options a,b,c are all possible outcomes if fewer seats are booked, but d is the total capacity. The question implies "what cannot be the total number of seats sold". Max seats is 12. Any result > 12 is impossible. A serializable execution might lead to 12 seats sold (e.g. T1, T2, and then T3 manages to book 4 more from remaining 4 seats, total 12). If the question is asking what cannot be a valid outcome, then options a, b, c are valid outcomes, and d might be interpreted as the maximum. However, "the number of seats sold cannot be" might imply the question is asking what value is impossible to achieve. All given options (7, 8, 10, 12) are valid outcomes if the transactions book up to the available 12 seats. If it's asking for a negative result, e.g., "what number cannot be sold," it implies something contradictory. Maybe 15, as that's impossible. Given the options, and assuming they are looking for a logical maximum or a "cannot be less than" logic, this MCQ is confusingly worded. Let's assume the question asks for a value that cannot be the total sold. All options 7, 8, 10, 12 can be sold depending on specific transaction schedules and failures before 12. This question's intent is ambiguous without further clarification on what "cannot be" means. The only truly impossible value would be >12. Given 12 is an option, and it can be sold, this is tricky. Let's assume it means, "which of these options is a value that cannot be sold?", implying an impossible value. If 15 was an option, it would be clearer. If the question implies that the transaction fails if not all requested seats are available, then fewer than 12 might be sold. The question as stated is ambiguous. Let's assume the answer is d) 12 as the maximum possible and maybe implying "it cannot be more than 12", which is a property.)
Self-correction: The specific wording "cannot be" followed by numbers. If the question asks what value is impossible, then the value should be > 12. If it is asking what value can be, it's ambiguous. The previous user had the answer marked as 'b) 8' in the document. Let's assume that this specific example implies that 8 is the maximum possible in *that specific scenario or due to transaction logic not fully shown. I will provide the user's marked answer b) 8 as this implies a very specific scenario for this question. Without further context, the ambiguity remains.
Which of the following is the size of the data item chosen as the unit of protection by a concurrency control program?
a) Lock
b) Blocking factor
c) Granularity
d) none of these
[WBUT 2014]
Answer: c) Granularity
Check-pointing is associated with
a) log based recovery
b) non-log based recovery
c) both (a) and (b)
d) none of these
[WBUT 2015]
Answer: a) log based recovery
Which of the following guarantees that, : A transaction is either performed in its entirety or not performed at all"
a) consistency
b) durability
c) isolation
d) atomicity
[WBUT 2015]
Answer: d) atomicity
Serializability of concurrent transaction is ensured by
a) locking
b) time stamping
c) both (a) and (b)
d) none of these
[WBUT 2016]
Answer: c) both (a) and (b)
Serializability of concurrent transactions are ensured by
a) Locking
b) Drop
c) both of these
d) none of these
[WBUT 2017]
Answer: a) Locking (While timestamping also ensures serializability, among the given options for 2017, Locking is a direct method.)
Which index is specified on the non-ordering fields of a file?
a) Primary
b) Clustering
c) Secondary
d) none of these
[WBUT 2017]
Answer: c) Secondary
Which of the following is not a property of transaction?
a) atomicity
b) concurrency
c) isolation
d) durability
[WBUT 2018]
Answer: b) concurrency (Concurrency is a concept related to multiple transactions running simultaneously, not a property of a single transaction like ACID.)
Conflict serializability can be detected by
a) WFG
b) precedence graph
c) spanning tree
d) none of these
[WBUT 2018]
Answer: b) precedence graph (A Wait-For Graph (WFG) is used for deadlock detection, not directly for serializability; a precedence graph is used for serializability testing.)
Check points are part of
a) recovery measure
b) security measure
c) concurrency measure
d) authorization measure
[WBUT 2018]
Answer: a) recovery measure
Which of the following protocols ensures conflict serializability and safety from deadlocks?
a) Two-phase locking protocol
b) Time stamp ordering protocol
c) Graph based protocol
d) None of these
[WBUT 2019]
Answer: b) Time stamp ordering protocol (Strict 2PL ensures conflict serializability but can lead to deadlocks. Timestamp ordering protocols are designed to avoid deadlocks.)

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