Final Exam (DBMS Srm)

The correct answer is "SELECT * FROM empinfo WHERE ename like '[d-p]%';". This query uses the LIKE operator with a pattern '[d-p]%' to retrieve all the rows from the empinfo table where the ename column starts with any letter from 'd' to 'p'. The '%' wildcard is used to match any characters after the specified pattern.

The condition for total participation of an entity in a relation is that the minimum cardinality should be one. This means that every entity in the relation must be associated with at least one instance of another entity. If the minimum cardinality is set to zero, it would allow for the possibility of an entity not being associated with any other entity in the relation, which would not fulfill the condition of total participation. Therefore, the correct answer is that the minimum cardinality should be one.

Referential integrity ensures that relationships between tables in a database are maintained accurately. When a delete operation is performed, it may violate referential integrity if it removes a record that is referenced by another table. This means that a record cannot be deleted if it is being referenced by another table, as it would result in orphaned records or broken relationships. Therefore, the correct answer is referential integrity.

To create a database, the privilege required is SYSDBA. SYSDBA is a powerful privilege that allows a user to perform administrative tasks, including creating and managing databases, as well as performing backup and recovery operations. This privilege is typically granted to database administrators who need full control over the database system. DBA and SYSOPER privileges do not have the necessary permissions to create a database. RESOURCE privilege is a lower level privilege that grants the ability to create and manage schema objects within a database, but not to create a database itself.

The correct answer is "All 4 constraints." An insert operation may violate all four constraints, which include key constraint, domain constraint, referential integrity, and entity integrity. The key constraint ensures that each record in a table has a unique identifier, and violating this constraint would result in duplicate keys. The domain constraint defines the valid values for a column, and violating this constraint would mean inserting an invalid value. Referential integrity ensures that relationships between tables are maintained, and violating this constraint would result in inserting a foreign key that does not exist in the referenced table. Lastly, entity integrity ensures that each record in a table has a unique primary key value, and violating this constraint would mean inserting a duplicate primary key.

The correct answer is "Project." In relational algebra, a binary operator is an operation that takes two relations as input and produces a new relation as output. Join and Semi Join are examples of binary operators as they combine two relations based on a common attribute. However, Project is a unary operator as it only operates on a single relation and selects specific attributes to be included in the resulting relation. Assignment is not a binary operator, but rather a concept used in programming or database management systems to assign values to variables or attributes.

The given SQL statement performs selection, projection, and join capabilities of a SELECT statement.

- Selection: It filters the rows from the EMP and DEPARTMENT tables based on the condition e.DEPARTMENT_ID = d.DEPARTMENT_ID, selecting only the rows where the department IDs match.
- Projection: It selects specific columns from the EMP and DEPARTMENT tables, namely e.EMPLOYEE_ID, e.LAST_NAME, e.DEPARTMENT_ID, and d.DEPARTMENT_NAME.
- Join: It combines the rows from both tables based on the common department ID column, creating a result set that includes data from both tables.

A view can be created as a join on two or more tables. This means that when creating a view, it is possible to combine data from multiple tables by specifying the necessary join conditions. This allows for a more efficient and organized way of retrieving and manipulating data from multiple tables, as the view can be treated as a single virtual table. By using views, complex queries involving multiple tables can be simplified and reused.

Tuple relational calculus is a non-procedural language because it specifies what data is needed without specifying how to retrieve it. It focuses on the logical representation of the desired data and leaves the implementation details to the database management system. This allows for a more declarative and abstract approach to querying and manipulating data, making it easier for users to express their requirements without having to worry about the specific steps to achieve them.

The given set of functional dependencies F can be simplified to the canonical cover A->B, B->C. This means that attribute A determines attribute B, and attribute B determines attribute C. This is the simplest form of the functional dependencies that still preserves all the dependencies in the original set.

If every attribute in a table is a candidate key, it means that each attribute uniquely identifies a tuple in the table. This implies that there are no partial dependencies or functional dependencies on any subset of attributes. Therefore, the table is in Boyce-Codd Normal Form (BCNF), which is a higher level of normalization than 1NF, 2NF, and 3NF. In BCNF, all non-trivial functional dependencies are eliminated, ensuring that the table is free from redundancy and anomalies.

The phantom phenomenon refers to a situation in which a query in a database returns extra rows that do not actually exist. This can occur when an insert operation is performed concurrently with a query. If the query is executed before the insert operation is completed, it may not be aware of the newly inserted rows, leading to the phantom phenomenon. Therefore, the correct answer is "Insert" as it is the operation that can cause this phenomenon.

This graph-based locking protocol ensures both serializability and deadlock freedom. Serializability is achieved because the protocol enforces a strict order of locking vertices, ensuring that conflicting operations do not occur simultaneously. Deadlock freedom is guaranteed because the protocol requires a transaction to visit all the parents of a vertex before locking it, preventing cycles in the locking order and avoiding potential deadlocks. Therefore, both properties are ensured by this locking protocol.

The given relation Student has attributes class, section, Roll, name, and address. It is mentioned that for any section, class, and roll, there is only one address, and for one address, there is only one name. This indicates a functional dependency between the attributes.

In the 2nd Normal Form (2NF), the relation should be in 1NF and there should be no partial dependencies. Since the given relation satisfies these conditions, it can be considered to be in 2NF.

Entity integrity refers to the rule that states that the primary key of a table must have a unique value and cannot be null. In other words, every record in a table must have a valid and unique identifier. If the primary key value is null in a new tuple, it violates the entity integrity constraint because it means that the record does not have a valid identifier.

The USING clause is used in three cases:
1) When the tables to be joined have columns of the same name but different data types.
2) When the tables to be joined have columns with the same name and compatible data types.
3) When you want to use a NATURAL join, but you want to restrict the number of columns in the join condition.

When a transaction reads a data item after it is written by an uncommitted transaction, it may lead to an irrecoverable error in a database system. This is because the uncommitted transaction's changes are not yet finalized and may be rolled back. If the subsequent transaction reads the data item before the changes are committed, it may retrieve incorrect or inconsistent data, leading to an irrecoverable error in the system.

In the top-down database design approach, the input taken is the entity. This means that the design process starts by identifying the main entities or objects that need to be represented in the database. These entities are the key elements that the database will store information about. By focusing on the entities first, the design process can then move on to defining the relationships between these entities, creating ER diagrams, and determining the attributes or properties of each entity.

If transaction 'A' sees the effects of transaction 'B', it means that 'A' reads data that has been modified by 'B'. If 'B' then aborts, it means that its changes are rolled back and not committed. In this case, if 'A' were to continue and commit its changes, it would lead to an inconsistent state because it has already seen the effects of 'B' which are now being rolled back. To maintain recoverability, where a transaction can be rolled back if needed, 'A' also needs to be aborted in this scenario. Therefore, the schedule is recoverable.

A surrogate key is similar to an artificial key because it is a unique identifier that is created solely for the purpose of identifying records in a database. Like an artificial key, a surrogate key does not have any inherent meaning or relationship to the data it represents. It is typically generated automatically by the database system and helps to ensure data integrity and improve performance in database operations.

Cascadelessness refers to the property in database systems where a transaction's read operations are not affected by any uncommitted changes made by other transactions. By allowing transactions to only read committed data, it ensures that any changes made by other transactions are already finalized and will not be rolled back. Similarly, by allowing transactions to only read their own version of data, it ensures that the transaction is isolated from any uncommitted changes made by other transactions. Therefore, both of these approaches ensure cascadelessness by preventing the reading of uncommitted data.

The trigger creation will fail because the statement trigger should have been defined as a row trigger.

An outer join is used when the columns being joined have NULL values and when the tables being joined have both matched and unmatched data. In an outer join, all the rows from one table are included in the result set, even if there is no match in the other table. This allows for the inclusion of NULL values and both matched and unmatched data in the output.

Physical data independence refers to the ability to modify the internal schema of a database without affecting the external schema or the way data is accessed and manipulated by users or applications. This means that changes to the physical storage structures, such as adding or removing indexes or reorganizing data, can be made without requiring any modifications to the external schema. Logical data independence, on the other hand, refers to the ability to modify the conceptual schema without impacting the external schema. External data independence refers to the ability to modify the external schema without affecting the way data is stored internally. None of these options fully align with the given explanation, therefore, the correct answer is Physical Data Independence.

The given schedule is view serializable because it can be transformed into an equivalent serial schedule by preserving the order of read and write operations on each data item. However, it is not conflict serializable because there is a conflict between transactions T1 and T2, where T1 writes to data item A and T2 reads from the same data item.

Precedence graph can be used to test conflict serializability. Conflict serializability is a property of a schedule in a database system, which ensures that the final result of executing concurrent transactions is equivalent to the result of executing them in some serial order. Precedence graph helps in determining if there is any conflict between the operations of different transactions in a schedule, by representing the transactions as nodes and the conflicts as edges in the graph. Therefore, the correct answer is conflict serializability.

The main task carried out in the Fourth Normal Form is to remove repeating attributes to separate tables. This is done to eliminate redundancy and improve data integrity. By separating repeating attributes into their own tables, we can ensure that each table represents a single entity and that there is no data duplication. This normalization form helps to maintain data consistency and allows for more efficient data storage and retrieval.

The concept of shadow paging is used to ensure atomicity. Shadow paging is a technique used in database systems to provide transaction atomicity. It involves creating a duplicate copy of the database before any modifications are made. This duplicate copy, known as a shadow page, allows for the changes to be made in isolation without affecting the original database. If a transaction fails or is aborted, the changes made in the shadow page can simply be discarded, ensuring that the original database remains unchanged. This ensures that transactions are either fully completed or fully rolled back, maintaining the atomicity property.

The correct answer is: SELECT employee_id, d.department_id, department_name, salary FROM employees e JOIN departments d ON e.department_id = d.department_id;

This SQL statement is equivalent to the original statement because it uses the JOIN keyword to combine the "employees" and "departments" tables based on the "department_id" column. It also selects the necessary columns: employee_id, department_id, department_name, and salary. The alias "e" is used for the "employees" table and "d" is used for the "departments" table. This statement ensures that only the rows with matching department IDs are included in the result.

The decomposition of R into R1, R2, and R3 is lossless because all the attributes of R are preserved in the decomposition. However, it is not dependency preserving because the dependency A->BC is lost in the decomposition. In R1, we only have A, B, and C, but not D or E which are dependent on A. Therefore, the correct answer is "Lossless but not dependency preserving."