Database Management System: Key Concepts and SQL Techniques

What is a Data Dictionary?

A data structure that stores metadata about the database, including information about tables, fields, and relationships.

What is Locking (or Serialization)?

A DBMS mechanism that ensures concurrent transactions are executed in a sequence that achieves the same result as if they had been executed one after the other.

What is Recovery in DBMS?

The function of a DBMS that involves restoring the database to a correct state following a hardware or software failure.

What is a Transaction Log?

A component of the DBMS that logs all database changes, including who made the change, when, and what the original value was, to assist with recovery.

What is Data Independence?

The ability to change the database structure without requiring changes to the programs that access the database.

What is Synchronization in DBMS?

The process of exchanging all updated data between a master database and a replica copy to keep them consistent.

What is Referential Integrity?

An integrity rule that ensures all values in a foreign key column match values in the primary key column of the related table.

What is the GRANT SQL statement?

An SQL statement primarily used by the DBA to define authorization rules and grant specific access permissions to users.

What is Security in the context of databases?

The prevention of unauthorized access, intentional or accidental, to the database.

What is Archiving?

The process of saving old data that is no longer considered 'active' but must be retained to satisfy governmental laws and regulations.

What are Views in DBMS?

A feature used to hide certain rows or columns from unauthorized users, thereby enforcing security policies.

What is a Test System (Sandbox)?

An environment used by programmers to develop new programs and modify existing ones before they are deployed.

What is a Distributed Database Management System (DDBMS)?

A system where the database is physically divided among computers connected by a communications network but appears logically as a single database.

What is a Global Deadlock?

A deadlock that involves transaction updates across more than one site in a distributed database.

What is Time-variant data?

Data that changes over time, which is a primary characteristic of data stored in a data warehouse.

What is Encapsulation in OODBMS?

A key feature that relates to the way data and associated actions are managed by encapsulating them into objects.

What are Methods in OODBMS?

Actions defined for a class that are executed when a user sends a message to the object.

What does the + symbol indicate in UML notation?

Public visibility for an attribute or method.

What is Location Transparency?

A type of DDBMS transparency that ensures users are not aware that a logical object is divided and managed across various physical locations.

What is the role of the precompiler in Embedded SQL?

To translate the SQL statements into function calls or host language statements.

What is Procedural SQL?

A technique that extends SQL with control flow statements like loops and conditionals.

What does JDBC stand for?

Java Database Connectivity.

What is the Driver Manager in JDBC?

An API component responsible for connecting the Java application to the correct database-specific driver.

What method is used for executing a SELECT query in JDBC?

executeQuery() method of the JDBC Statement interface.

What is the primary advantage of using a PreparedStatement?

It supports query parameters for repeated, faster execution and prevents SQL injection.