Databases play a central role in the modern information society by managing structured collections of data and enabling efficient access to them. From simple applications to complex enterprise systems, databases are the backbone of many technologies and services. Different types of databases are used in this context. This diversity makes it possible to adapt databases to the specific requirements and challenges of different applications. 

What is a database? 

A database is understood to be a structured collection of Datawhich are stored and managed in a computer system. It is used to organise, store and retrieve information efficiently. Databases can consist of one or more interconnected tables, with each table containing different data records. 

What are types of databases? 

There are several types of databases or so-called database models, which differ in their logical structure. The properties and possible fields of application of hierarchical, object-orientated, document-orientated, relational and non-relational databases are described below. 

Hierarchical databases 

Hierarchical databases organise data in a Tree structure, with each level having parent and child data records. One advantage of this database model is efficient navigation, as data can be navigated and retrieved quickly. This structure is well suited to applications such as file systems, company management systems and network topologies, which have strict hierarchical relationships between the data. 

Object-orientated databases 

Object-orientated databases store data in the form of so-called objects that contain both attributes and methods can. Attributes are properties of objects, while methods describe the behaviour/algorithms of objects. This logic is similar to that of object-orientated programming. By using objects, data can be organised in a modular way and complex relationships can be mapped. Object-orientated databases are particularly suitable for complex data models and applications that require a high degree of flexibility. One example of this is multimedia applications, which can be efficiently managed using different types of data such as images, videos and audio. CAD software can also be managed with object-orientated databases in order to store complex 3D models and their relationships. 

Document-orientated databases 

Save and organise document-oriented databases Data in the form of documents and can contain structured or unstructured dataThis enables flexible data modelling without a fixed schema. Document-orientated databases are usually stored in JSON or XML format. This type of database is easily scalable and can therefore also process large amounts of data efficiently. Document-orientated databases are well suited for content management systems to store and manage text, images and videos, for example. This type is also suitable for web applications and big data analyses, as it can efficiently process unstructured or semi-structured data without data modelling. 

Relational databases 

Using relational databases Tables consisting of data in rows and columns. The data records are organised in the respective rows and the properties in the respective columns. They use complex query languages such as SQL to manipulate and query data. Relational databases support complex relationships between tables that are defined by primary and foreign keys. They usually offer transaction support with the four ACID properties (Atomicity, Consistency, Isolation, Durability) to ensure data integrity and consistency. 

Relational databases are widespread and are used in various industries and applications, such as in finance to store and manage transaction data such as account movements and transaction histories. They are used on e-commerce platforms to manage product data, orders, customer information and transactions. 

Non-relational databases 

Non-relational databases, also known as NoSQL databasesuse Various approaches to data organisationwhich are not based on the relational model. They offer flexibility and high performance for different types of data, such as structured, unstructured or semi-structured data. They are highly scalable and can be easily run on distributed systems to process large amounts of data.  

Non-relational databases are often used in Big data applications as they can efficiently process unstructured or semi-structured data without requiring complex data modelling. Other areas of application are Cloud computing and real-time analyses for processing and analysing data streams in real time, such as in the advertising industry or in the Internet of Things (IoT).  

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Components and mode of operation 

A database consists of various components that work together to store, manage and retrieve data. The main components of a database include the database management system, the database model, the actual data, the query language, security mechanisms and indices. 

The Database management system (DBMS) is the central software that manages the database. It provides interfaces for users and applications to access, save, update and query the data. 

The Database model defines the structure of the database, including the way in which data is organised and linked together. The various database models were briefly explained in the previous paragraph. The chosen model influences the possibilities of data modelling and querying. 

The Data / Information represent the core of every database. While the data in a relational database is organised as tables, in document-oriented databases, for example, it is stored in the form of documents. The structure of the data can differ depending on the database model selected. 

The same applies to the Query language. The query language enables users and applications to retrieve, manipulate and analyse data. SQL is the common query language for relational databases. Other database models may use specific query languages that are customised to their structure and functionality. 

Security mechanisms are used to protect data from unauthorised access, loss or damage. This includes authentication, authorisation, encryption and monitoring functions that ensure that only authorised users can access and manipulate the data.  

Indices are special structures that are used to speed up access to data. They contain sorted references to data records based on specific attributes, which improves the efficiency of search and query operations. Indexes are used to optimise the performance of database queries, especially with large amounts of data. 

The How a database works comprises various processes, including data manipulation, data retrieval, transaction management and ensuring data integrity. Data manipulation refers to the insertion of new data records, the updating of existing data records and the deletion of data records. 

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Popular database management systems for companies

The database management system (DBMS) monitors and coordinates the processes of a database to ensure efficient and reliable database utilisation. It also manages the database's resources, including storage space, physical data access, connection pools and query processing, in order to achieve optimum performance and maintain data integrity.  

Common database management systems are 

MongoDB 

MongoDB is a document-orientated NoSQL database that offers flexibility, scalability and high performance. It uses a flexible data model based on BSON (Binary JSON) and enables natural data representation. MongoDB offers horizontal scalability and a wide range of functions for data analysis and processing. It is well suited for big data analyses, content management systems and real-time applications. 

Advantages: 

• Scalability 
• Flexible data model 
• Performance with large amounts of data 

Disadvantages: 

• Performance losses due to consistency model 
• Complexity 

DynamoDB 

DynamoDB is a fully managed NoSQL database service from Amazon Web Services (AWS) that provides a highly available, scalable and performant database solution. It uses a key-value based data model and offers automatic scaling and fast performance for read and write operations. DynamoDB is particularly suitable for applications in the cloud environment.  

Advantages: 

• Complete management 
• Automatic scaling 
• Fast performance 

Disadvantages: 

• High licence costs 
• Limited query options 

MySQL 

MySQL is an open source relational database known for its reliability, performance and broad support. It uses the relational data model and offers an extensive range of functions for data management and query optimisation. MySQL is widely used in a variety of applications and industries. 

Advantages: 

• Reliability 
• Broad support and community 
• Available free of charge 

Disadvantages: 

• Limited scalability compared to NoSQL databases 
• Complexity of managing large amounts of data 

Oracle Database 

Oracle Database is a relational database known for its scalability, security and performance. It offers extended functions for database administration, transaction management and high availability. Oracle Database is often used in mission-critical applications that have high requirements for data integrity and reliability. 

Advantages: 

• Scalability 
• Security 
• Power 

Disadvantages: 

• High licence costs 
• Complexity in configuration and administration 

Microsoft SQL Server 

Microsoft SQL Server is a relational database platform from Microsoft that is known for its integration with other Microsoft products and technologies. It offers a wide range of functions for data management, business intelligence and development tools. Microsoft SQL Server is widely used for Windows-based applications and environments. 

Advantages: 

• Integration with other Microsoft products 
• Extensive functions for business intelligence 
• Powerful development tools 

Disadvantages: 

• Platform dependency 
• High licence costs 

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Organisation of data as a strategic approach

Databases are important tools that make it possible to store, manage and retrieve data efficiently. The variety of database models, including hierarchical, object-orientated, relational and non-relational approaches, offers many options for a wide range of applications and requirements. In this context, database management systems play a decisive role by taking over the administration and control of databases. There are many providers of database management systems on the market. Each of these systems has its own characteristics, strengths and weaknesses, which must be taken into account depending on the specific requirements and objectives of an application.