Database Management System Exercise Solutions

[Yi Pressimone]

SQLstands for Structured Query Language and it is an ANSI standard computer language for accessing and manipulating database systems. It is used for managing data in relational database management system which stores data in the form of tables and relationship between data is also stored in the form of tables. SQL statements are used to retrieve and update data in a database.

The best way we learn anything is by practice and exercise questions. We have started this section for those (beginner to intermediate) who are familiar with SQL. Hope, these exercises help you to improve your SQL skills. Currently following sections are available, we are working hard to add more exercises. Happy Coding!

A database management system (DBMS) is a computer program designed to manage a large amount of structured data, and run operations on the desired data requested by the users. The best example of DBMS is Banking. All the transactions that take place are based on a defined software program which keeps track of all the data.

The concept of DBMS is an important topic from a Computer Knowledge perspective. It also forms an integral part of the syllabus for major competitive exams. Thus, one must carefully go through the concept.

In this article, we bring you an introduction to the Database Management System along with its types and functions. Also, the advantages and components of a DBMS have been discussed in detail. Some sample questions on this topic have also been given further below in this article.

A collection of information which is managed such that it can be updated and easily accessed is called a database. A software package which can be used to manipulate, validate and retrieve this database is called a Database Management System.

Major Organisations and Banking firms choose to work using the Database Management System. It is because this system program helps the user and the administrator easily manage the data and information on the database.

As discussed earlier, the topic of DBMS is important from the perspective of competitive exams. Thus, to assist candidates to apprehend the type of questions which may be asked based on this concept, given below are a few sample DBMS questions and answers.

In the world of software development, choosing the right database is a crucial decision that can significantly impact your application's performance, scalability, and ease of use. With many options available, it can be challenging to determine the best database management system (DBMS) that will perfectly suit your needs.

A Database Management System (DBMS) is a specialized software designed to store, retrieve, and manipulate data. It acts as a mediator between the database, applications, and user interfaces to manage and organize data effectively. The system provides a comprehensive suite of tools to govern databases, ensuring data security, consistency, and integrity.

A DBMS supports various applications, from simple storage and retrieval tasks to complex data-driven systems, by implementing efficient data access and management practices. Additionally, the system can handle concurrent users, maintain transactional consistency, and provide robust backup and recovery options, making it an essential component in any data-centric environment.

A relational database management system (RDBMS) is an information repository that organizes data into tables consisting of rows (records) and columns (attributes that contain the properties of these records). Each table represents a relation, and the rows (also called tuples) hold individual records within that relation. RDBMSs have a predefined schema with a strict structure and clear dependencies between different data points.

So tables in relational databases are connected to other tables through primary key or foreign key relationships. A primary key is a unique identifier for each record in a table, ensuring that no two records have the same value for that specific column or set of columns. On the other hand, a foreign key is a column or a set of columns in one table that refers to the primary key in another table, establishing a link between them.

Despite these connections between tables, the term relational in relational database systems comes from the mathematical concept of relations. Dr. Edgar F. Codd proposed this idea as a new way to organize and manage data using principles from mathematics in his seminal paper "A Relational Model of Data for Large Shared Data Banks," published in 1970.

Scalability. Relational databases usually scale vertically, meaning data lives on a single server, and scaling is done by adding more computer (CPU, GPU, and RAM) power to that one server. However, switching from smaller to bigger machines often involves downtime. Scaling an SQL database between multiple servers (horizontal scaling) can be challenging as it requires data structure changes and additional engineering efforts.

Performance. Relational databases perform well with intensive read/write operations on small to medium datasets. They also offer improved speed of data retrieval by adding indexes to data fields to query and join tables. However, the performance may suffer when the amount of data and user requests grows.

Scalability. When the number of data and requests increases, non-relational or NoSQL databases are usually scaled horizontally by adding more servers to the pool. They share data between various servers where each contains only a part of the data, decreasing the request-per-second rate in each server.

Performance. Non-relational databases are known for their high performance: They have a distributed design, which lowers the performance load on the system and provides a large number of users with simultaneous access. Such databases can store unlimited data sets that come in all types and shapes. They are also quite flexible when it comes to changing data types.

Security. Unlike relational systems, NoSQL databases have weak security, making them a major concern for many infrastructures. While they may provide ACID guarantees, they are typically available within the scope of one database partition. However, some DBMSs offer advanced security features that meet strict security and compliance standards.

Free installation. The community edition of MySQL is free to download. With a basic set of tools for individual use, MySQL community edition is a good option, to begin with. Of course, there are other, prepaid versions for Enterprise or Cluster purposes with richer functionality. Nevertheless, if your company is too small to pay for one of them, the free-to-download model is the most suitable for a fresh start.

Scalability challenges. MySQL was not built with scalability in mind, which is inherent in its code. Theoretically, you can scale MySQL, but it will need more engineering effort than any of the NoSQL databases. So, if you expect one day your database will increase substantially, keep this limitation in mind or choose another DBMS option.

Broad functionality. MariaDB has introduced a lot of new features in the last few years. For instance, GIS support suggests smooth coordinate storage and location data queries. Dynamic columns allow a single DBMS to provide both SQL and NoSQL data handling for different needs. You can also extend its functionality with plugins that are available at MySQL via 3rd parties only. MariaDB is shipped with storage engines for NoSQL backend, legacy database migration tools, sharding options, and much more.

Still a growing community. Although MariaDB has substantial open-source contribution, its community has yet to grow much. Since this database management system was established not so long ago, the number of professionals involved is relatively small.

Since MariaDB is close to MySQL, it can be used to work with the same types of web-based applications. Additionally, you get extended location data storage, higher performance, and improved scalability.

Oracle is a relational database management system created and run by the Oracle Corporation. Among all the types of SQL databases, Oracle stands out. Currently, it supports multiple data models like document, graph, relational, and key-value within a single database. In its latest releases, it refocused on cloud computing. Oracle database engine licensing is fully proprietary, with both free and paid options available.

Innovations for daily workflow. Starting with the Oracle 12c release, when the software entered the hybrid cloud era, new cloud computing technologies appeared regularly. With every new release, Oracle tries to keep up with the innovation pace while focusing on information security, including active data guard, partitioning, improved backup, and recovery.

Financial institutions. Oracle is widely used in the financial sector, where data integrity and security are paramount. Banks, insurance companies, and investment firms often rely on Oracle to manage sensitive financial data and transactions.

Government and public sector. Oracle is often chosen for its robust features and security in government and public sector applications, including national security, healthcare, and transportation systems.

Great scalability. Vertical scalability is a hallmark of PostgreSQL. Considering that almost any custom software solution tends to grow, resulting in database extension, this particular option certainly supports business growth and development.

Support for custom data types. PostgreSQL natively supports many data types by default, such as JSON, XML, H-Store, and others. PostgreSQL takes advantage of it, being one of the few relational databases with strong support for NoSQL features. Additionally, it allows users to define their own data types. As your software business model may need different types of databases throughout its existence for better performance or application comprehensiveness, this option brings improved flexibility to the table.

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