Database

UML: activity diagram

UML: activity diagram

UML activity diagrams help you to graphically illustrate the chronological sequence of system processes in object-oriented programming. They show which actions take place in which order to execute an activity. With a finished diagram, you can create code frames using XML transfer. Or do you want to map business processes? We show examples of how to create an activity diagram, which symbols belong...

Database normalisation

Database normalisation

Redundancies occur when various details are combined in a single database table. These redundancies use up storage capacity and prevent efficient data processing. The relational database model offers strategies for splitting datasets among several linked tables, in a process called database normalisation. Find out what it’s all about with practical examples.

Raspberry Pi at a glance: 10 great Raspberry Pi projects

Raspberry Pi at a glance: 10 great Raspberry Pi projects

Raspberry Pi is an inexpensive small form factor PC that can behave like a standard computer in many respects. Users can use this innovative mini-computer for all kinds of functions, from setting up an operating system to surfing the web, to using it as a server or a media center, and much more besides. Discover 10 interesting Raspberry Pi projects to try out at home.

Databases

Databases

Databases are a fundamental part of our information society today. They organise electronic data and regulate access to it. Databases have a wide range of applications, both commercial and private. Each database system has a database management system based on a specific database model. Whilst the history of the database began with the hierarchical model, today the relational database model is the...

In-memory databases

In-memory databases

In-memory databases enable big data to be analysed and made available in real time. The quick access speeds are made possible by storing the data on the working memory – hence the name in-memory database. Traditional databases, on the other hand, are based on the method of storing data on the hard disk. How do in-memory databases differ from traditional database systems? And what are the go-to...

Protect sensitive data with a strong password

Protect sensitive data with a strong password

It only takes a few seconds for a hacker to gain access to your private data without you having any idea. More often than not, a password is the only means of protection when logging into online services; and if it is too obvious, it will not prove too much of a challenge for criminals to crack. There are numerous options to increase password security.

SQL JOIN

SQL JOIN

A major strength of the relational database model is that information is stored in separate database tables structured according to semantic relationships. This concept, known as normalisation, is the basis for data storage that is as redundancy-free as possible, but requires a mechanism with which data from different tables can be merged for queries. The different JOIN types provide users with...

SQL OUTER JOIN

SQL OUTER JOIN

OUTER JOINs are queries that take place across several database tables. There are LEFT OUTER JOINs, RIGHT OUTER JOINs and FULL OUTER JOINs. Each of these JOIN types has a larger result set than the INNER JOIN. But what exactly is the difference between the individual types? Here, we will distinguish OUTER JOINs from INNER JOINs, compare the different subtypes of OUTER JOINs and explain how they...

Relational databases

Relational databases

With relational database systems, you use tables to store and manage information. This sounds simple but involves quite complex concepts such as normal forms, key relationships, and JOINs. This article will introduce the basics of the relational database model, compare its advantages and disadvantages, and delimit this type of data storage from alternative approaches, like object databases,...

Set up ownCloud with Raspberry Pi

Set up ownCloud with Raspberry Pi

With ownCloud software, your Raspberry Pi can be used as a private cloud, performing the same kind of tasks as clouds from major providers such as Google, Amazon, and Dropbox. Cost-effectiveness is just one of many the benefits of creating your own personal cloud; another is the privacy and security of your data. This step-by-step Raspberry Pi cloud tutorial explains how to set up ownCloud.