Infromation Technology Quiz: Database Management

The correct answer is top-down approach because E-R modeling techniques typically involve starting with a high-level view of the system and gradually refining it by breaking it down into smaller and more detailed components. This approach allows for a systematic and organized way of designing the system, starting from the overall structure and then moving towards the specific details.

The correct answer is "SELECT city, temperature, condition FROM weather WHERE condition NOT IN ('sunny', 'cloudy')". This query will retrieve the names of cities along with their temperature and condition where the condition is neither sunny nor cloudy. It uses the NOT IN operator to exclude the conditions 'sunny' and 'cloudy' from the result set.

The relationship used to represent a specialization entity is ISA. This relationship indicates that one entity is a specialized version of another entity. It is commonly used in inheritance hierarchies, where the specialized entities inherit attributes and behaviors from the general entity.

In a one-to-many relationship, the entity that is on the one side of the relationship is called a "Parent" entity. This is because the parent entity can have multiple child entities associated with it, but each child entity can only have one parent entity. The parent entity often acts as the main or primary entity in the relationship, while the child entities depend on the parent entity for their existence or attributes.

In an E-R diagram, the total participation by entities is represented by a double line. This indicates that every entity in the relationship must participate fully in the relationship. It means that each entity is connected to the relationship through a mandatory participation, and cannot exist without being associated with the relationship. The double line represents a strong relationship between the entities and emphasizes the requirement for total participation.

The ER model includes additional concepts like specialization, generalization, and categorization. Specialization refers to the process of defining subclasses within an entity class, where each subclass inherits the attributes and relationships of the superclass. Generalization, on the other hand, is the process of defining a superclass that encompasses multiple subclasses. Categorization involves grouping similar entities into categories based on common characteristics. Therefore, all of the above concepts are included in the ER model.

A functional dependency is a relationship between attributes in a database. It describes how the value of one attribute determines the value of another attribute. In other words, if we know the value of one attribute, we can determine the value of another attribute based on this relationship. This relationship exists between attributes, not tables, rows, or relations. Therefore, the correct answer is "Attributes".

In a two-phase locking protocol, the transaction releases locks in the shrinking phase. This phase occurs after the transaction has completed its execution and is ready to release the locks it acquired during the growing phase. During the shrinking phase, the transaction releases the locks in a reverse order of their acquisition, ensuring that no other transaction can access the released resources. This allows for better concurrency control and prevents conflicts between transactions.

Isolation refers to the property of a database system that ensures that concurrent transactions do not interfere with each other. It ensures that each transaction is executed in isolation, as if it were the only transaction running. This is achieved by using various concurrency control techniques such as locking and multiversion concurrency control. By maintaining isolation, the database system can prevent issues such as dirty reads, non-repeatable reads, and phantom reads, which can occur when multiple transactions access and modify the same data simultaneously.

A non-serial interleaving of T1 and T2 for concurrent execution leads to a schedule that is not conflict Serializable. Conflict Serializable means that the final result of the schedule is the same as if the transactions were executed serially in some order. In this case, if T1 and T2 are executed concurrently, there is a possibility of conflicts between their read and write operations on the shared data items P and Q. Therefore, the resulting schedule may not be conflict Serializable.

The correct answer is ALTER TABLE. This command is used in SQL to make changes to the structure of a table, including changing its storage characteristics. The other options, MODIFY TABLE and CHANGE TABLE, are not valid SQL commands. Therefore, the correct command to use in this case is ALTER TABLE.

An entity-relationship diagram is a graphical representation that shows the logical structure of a database. It depicts the entities (objects or concepts) in the database, their relationships with each other, and the attributes (properties) of each entity. This diagram helps in understanding the relationships and dependencies between different entities in the database, making it easier to design, analyze, and communicate about the database structure.

The correct answer is "More than zero but less than that of an equivalent 3NF decomposition". This means that when a relation is decomposed into BCNF, there will still be some redundancy present in the resulting set of relations. However, this redundancy will be less than what would be present in an equivalent 3NF decomposition. BCNF aims to eliminate redundancy by ensuring that every non-trivial functional dependency is represented by a candidate key. However, it does not guarantee complete elimination of redundancy, unlike 3NF decomposition.

Immediate database modification technique uses both undo and redo. Undo allows for the reversal of changes made to the database, ensuring that any incorrect or unwanted modifications can be reverted. Redo, on the other hand, enables the reapplication of changes that were previously undone, ensuring that all modifications are properly recorded and applied to the database. By utilizing both undo and redo, the immediate database modification technique ensures data integrity and consistency.

The constraint that the sum of the accounts x and y should remain constant is that of consistency. Consistency ensures that the data remains in a valid state before and after the execution of a transaction. In this case, the sum of the accounts x and y should remain the same before and after the transaction. If the transaction deducts 50 from x, it should add 50 to y to maintain the consistency of the total sum of the accounts.

The given information states that whenever attribute A appears, it is always matched with the same value of attribute B, but not the same value of attribute C. This implies that there is a direct relationship between A and B, where A determines the value of B. However, there is no clear relationship between A and C, as A does not determine the value of C. Therefore, the correct answer is A → B, indicating that attribute A determines the value of attribute B.

Two phase locking is a protocol that guarantees that a set of transactions becomes serializable. This protocol ensures that each transaction acquires all the necessary locks before it starts executing and releases all the locks only after it completes. The protocol consists of two phases: the growing phase, where transactions acquire locks, and the shrinking phase, where transactions release locks. By following this protocol, conflicts and inconsistencies between transactions are avoided, ensuring that the set of transactions can be executed in a serializable manner.

A tablespace is a logical grouping of database objects, such as tables and indexes, that is used to facilitate security, performance, and availability. It allows for the organization and management of these objects within a database, providing a way to allocate and manage storage space efficiently. By grouping related objects together, it becomes easier to implement security measures, optimize performance, and ensure the availability of database objects.

The 3NF (Third Normal Form) is considered adequate for normal relational database design. This normal form ensures that there are no transitive dependencies within a table. It eliminates any non-key attributes that depend on other non-key attributes, promoting data integrity and reducing redundancy. By achieving 3NF, a database design is considered to be well-structured and efficient, making it suitable for most applications.

The default completeness constraint is partial. This means that unless otherwise specified, a generalization or specialization is assumed to be partial. In a partial generalization or specialization, not all entities or attributes are included in the higher-level entity or specialization. This allows for flexibility and allows for entities or attributes to be excluded if they are not relevant to the higher-level concept.

A unit of storage that can store one or more records in a hash file organization is denoted as "buckets". In a hash file organization, records are distributed across different buckets based on a hashing function. Each bucket can hold multiple records, and the hashing function determines which bucket a record should be placed in. This allows for efficient retrieval of records based on their keys, as the hashing function helps narrow down the search to a specific bucket. Therefore, "buckets" is the correct answer for this question.

The most important hardware component for the operation of a database management system is a high-speed large capacity disk. This is because a database management system requires storage space to store and retrieve large amounts of data efficiently. A high-speed large capacity disk allows for faster data access and retrieval, which is crucial for the smooth functioning of a database management system.

If every functional dependency in set E is also in the closure of F, it means that the closure of F contains all the functional dependencies in E. This implies that all the functional dependencies in E can be derived from F, indicating that E is covered by F.

Wait-die is a technique used in concurrency control to prevent deadlock in a transaction system. It allows a transaction with a smaller timestamp to wait for a data item held by a transaction with a larger timestamp. If a transaction with a smaller timestamp requests a data item held by a transaction with a larger timestamp, it is allowed to wait. However, if a transaction with a larger timestamp requests a data item held by a transaction with a smaller timestamp, the smaller timestamp transaction is rolled back (dies). This ensures that older transactions are given priority and prevents deadlock from occurring.

A disjointness constraint requires that an entity belong to no more than one lower-level entity set. This means that an entity can only be associated with one specific lower-level entity set and cannot belong to multiple lower-level entity sets simultaneously. This constraint ensures that the relationships between entities are clear and unambiguous, preventing any confusion or duplication of data.

The highest normal form of this relation schema is 3NF. This is because all the functional dependencies in the schema are already in 3NF. The first two functional dependencies (1) name, courseNo->grade and (2) rollNo, courseNo->grade are both already in 3NF as they have a single attribute on the right-hand side. The third functional dependency (3) name->rollNo and the fourth functional dependency (4) rollNo->name are also in 3NF as they have a transitive dependency. Therefore, the relation schema is already in 3NF and cannot be further decomposed.

The given relational schema is not in 2NF because there is a partial dependency between the attributes. The FDs (functional dependencies) AB->CD and DE->P indicate that attributes C and P depend on only a part of the candidate key (AB and DE respectively). Therefore, it violates the second normal form (2NF) which requires that non-prime attributes should not be functionally dependent on only a part of the candidate key.

A deadlock occurs when multiple transactions are waiting for each other to release the data items they hold. In this situation, none of the transactions can proceed, resulting in a deadlock. This can happen when there is a circular dependency among the transactions, causing them to wait indefinitely for each other. Deadlocks can severely impact the performance and efficiency of a system, and proper deadlock detection and prevention mechanisms are necessary to avoid them.

The two-phase lock is a procedure for acquiring the necessary locks for a transaction where all necessary locks are acquired before any are released. This means that in the first phase of the locking process, all required locks are acquired, and in the second phase, all locks are released. This ensures that the transaction maintains consistency and avoids any conflicts or inconsistencies that may arise if locks are released before all necessary locks are acquired.

The highest level in the hierarchy of data organization is called a database. A database is a structured collection of data that is organized and stored in a way that allows for efficient retrieval, manipulation, and management. It typically consists of multiple interconnected data files that are organized and structured using a database management system (DBMS). A database provides a centralized and integrated view of data, allowing users to efficiently store, retrieve, and analyze large amounts of information.

The given answer states that Book is in 2NF and Collection is in 3NF. This means that Book satisfies the requirements of 2NF, which includes being in 1NF and having no partial dependencies, while Collection satisfies the requirements of 3NF, which includes being in 2NF and having no transitive dependencies. The functional dependencies given in the question indicate that Book has a partial dependency (Catalog_no depends on Title and Author) and Collection has a transitive dependency (Catalog_no determines Title, Author, Publisher, and Year). Therefore, the given answer correctly identifies the normalization levels for each scheme.

The given functional dependencies are CH→G, A→BC, B→CFH, E→A, F→EG. To determine the candidate keys, we need to find the minimal set of attributes that can uniquely identify all other attributes in the relation. By analyzing the given functional dependencies, we can see that the attributes A, B, C, and E are all candidate keys because they can determine all other attributes in the relation. Therefore, the relation R has 4 candidate keys.

Adding appropriate attributes to a weak entity set can convert it into a strong entity set. This is because weak entity sets depend on a strong entity set for their existence and cannot be uniquely identified on their own. By adding appropriate attributes, the weak entity set gains the ability to be uniquely identified and becomes a strong entity set. Generalization and aggregation are not the correct methods for converting a weak entity set into a strong entity set.

This query selects both the city and temperature columns from the weather table and orders the result set by the temperature column in ascending order. This means that the cities will be listed in increasing order based on their respective temperatures.

The current copy of the database is identified by a pointer called a Db-pointer, which is stored on disk. This pointer allows easy access to the location of the database and ensures that the correct version is retrieved when needed. By using a Db-pointer, the system can efficiently manage and update the database without confusion or errors.

A weak entity relationship is represented by a double diamond. A weak entity is an entity that cannot exist without the existence of another entity, known as the identifying entity. The double diamond symbolizes this dependency, indicating that the weak entity's existence is reliant on the identifying entity. This notation helps to visually distinguish weak entity relationships from regular entity relationships.

The correct answer is "Select year, avg(num credits) over (order by year rows 3 preceding) as avg total credits from tot credits;". This query calculates the average number of credits taken by students in each year, considering the three preceding tuples in the specified sort order. It uses the "rows 3 preceding" clause to include the current tuple and the two preceding tuples in the calculation of the average.

The decomposition of R into R1(A, B) and R2(C, D) is dependency preserving because the functional dependencies A -> B and C -> D are still preserved in the decomposed relations. However, it is not lossless join because there is no common attribute between R1 and R2 that can be used to join them and obtain the original relation R.

The given table is in 1NF (First Normal Form) because it satisfies the requirement that each attribute in a table must contain only atomic values. The functional dependencies F1->F3 and F2->F4 indicate that there are no repeating groups or multivalued dependencies in the table. However, the functional dependency (F1,F2)->F5 suggests that there may be a partial dependency, which violates the second normal form (2NF) requirement. Therefore, the table is not in 2NF or 3NF.

The given set of functional dependencies (FDs) F={CH→G, A→BC, B→CFH, E→A, F→EG} implies that there are partial dependencies present in the relation R. This means that there are attributes that depend on only a part of the primary key. Specifically, attribute B depends on attribute A, and attribute F depends on attribute E. Therefore, the relation R is in 1NF because it contains atomic values, but it is not in 2NF because it has partial dependencies.

The IS NULL operator is used to test if a column contains no data. It returns true if the column has a null value and false otherwise. This operator is commonly used in SQL queries to filter out rows that have missing or unknown values in a specific column.

Metadata refers to the information about the data in a database. It includes details such as the structure, format, and characteristics of the data. Metadata provides valuable insights into the data, allowing users to understand and effectively utilize the information stored in the database. It plays a crucial role in data management and helps in organizing, accessing, and analyzing the data efficiently. Hyperdata and Teradata are not relevant to the question, and therefore, the correct answer is metadata.

A prime attribute can be transitively dependent on a key in a BCNF relation. This statement is false because in BCNF (Boyce-Codd Normal Form), all non-key attributes must be functionally dependent on the entire primary key, and there should be no transitive dependencies. Transitive dependency occurs when a non-key attribute is functionally dependent on another non-key attribute, which violates BCNF.

The DBMS acts as an interface between the database application and the database. This means that the DBMS allows the database application to interact with the database by providing a set of tools and functions for managing the data stored in the database. The DBMS handles tasks such as data storage, data retrieval, data manipulation, and data security, ensuring that the database application can access and work with the data effectively.

The given schedules S1 and S2 are both conflict serializable. Conflict serializability means that the final result of the schedules is the same as if the transactions were executed one after the other in some order. In both S1 and S2, the conflicting operations (read-write or write-read) are executed in the same order as they appear in the original transactions T1, T2, and T3. Therefore, both schedules are conflict serializable.

Clustering file organization allows us to read records that would satisfy the join condition by using one block read. In clustering file organization, the records that are related to each other based on a common attribute value are stored physically close to each other on disk. This reduces the number of disk I/O operations required to retrieve records that satisfy a join condition, as the related records can be read in a single block read. This organization is particularly useful for improving the performance of join operations in database systems.

A data dictionary is a special file that contains all the mentioned information. It includes the names of all fields in all files, the data types of all fields in all files, and the widths of all fields in all files. This comprehensive file serves as a reference guide for understanding the structure and organization of the data within a database or system.

RAID level 1 refers to disk mirroring with block striping. In this level of RAID, data is duplicated on two separate disks, providing redundancy and fault tolerance. The data is also striped across the disks, allowing for improved read and write performance.

The given relation (Roll_number, Name, Date_of_birth, Age) is not in any of the above forms because it violates the third normal form (3NF) and Boyce-Codd Normal Form (BCNF). In 3NF, no non-key attribute (attribute not part of the primary key) should depend on another non-key attribute. Here, Age depends on Date_of_Birth, which is a violation. In BCNF, every determinant (attribute that determines another attribute) should be a candidate key. In this case, Age is not a candidate key, but it determines Eligibility, which violates BCNF. Therefore, the relation is not in 3NF or BCNF.

This decomposition is both lossy-join and lossless-join. It is lossy-join because the original relation Inst_dept cannot be reconstructed from the two decomposed relations (instructor and department) without losing information. It is also lossless-join because the natural join of the decomposed relations (instructor and department) will result in the original relation Inst_dept. Therefore, the correct answer is both a and b.