BE - Database Management Systems

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Categorize joins in the SQL. Explain each with suitable example.

A join is used to combine rows from two or more tables based on a related column between them. Joins are categorized into several types:

1. INNER JOIN

An inner join returns only the rows that have matching values in both
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Explain GRANT, REVOKE and SAVEPOINT commands with suitable example.

1. GRANT Command

The GRANT command is used to give specific privileges to a user or a role. Privileges may include SELECT, INSERT, UPDATE, DELETE, or even permission to grant privileges to
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Explain ACID properties of transaction.

a transaction is a single logical unit of work that consists of one or more database operations such as insert, update, delete, or retrieve. To ensure that the database remains correct and reliable even in the presence
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Which kind of queries are solved using division operator? Explain in detail.

The division operator (÷) in relational algebra is used to answer queries that involve the phrase “for all”.
It is particularly useful when
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What is role? How can we authorize a user using grant and revoke command? Give example.

a role is a named collection of privileges that can be assigned to users to simplify authorization management. Instead of granting individual permissions to each user, the database administrator can group related
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List and explain various types of Locks used for concurrency control.

locks are mechanisms used in concurrency control to synchronize access to the database by multiple transactions. They ensure that the database remains consistent when transactions execute simultaneously. A lock
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Define various approach used for Log based recovery

log-based recovery is a technique used to restore the database to a consistent state after a crash or failure. A log is a sequential record that stores all database operations performed by transactions. The log is
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Write a note on view serializability

when multiple transactions execute concurrently, the system must ensure that the outcome is correct and consistent.

One way to check correctness is through serializability, which means that the concurrent execution of transactions should
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Define transaction and its properties ?

In DBMS, a transaction is a single logical unit of work that consists of one or more database operations such as insert, delete, update, or retrieve. A transaction ensures
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What is decomposition? Explain dependency preserving decomposition with the help of example.

In Database Management Systems (DBMS), decomposition is the process of breaking a relation (table) into two or more smaller relations.

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