Hello, I am Pilar Angeles. Welcome to the specialization course relational database systems. These principles will be competed in six weeks, and you will be supported with videos and various documents that will allow you to learn in a better simple way. How several types of information systems and databases are available to solve different problems at the industry. In the first module named information systems, we will learn how people, hardware, software, networks, techniques and procedures work together to a domain transactional processes that companies need for their daily operations. Let us start. Nowadays, we share a large amount of information every day. Have you ever thought about how much information you get or share on a daily basis? Share. Information that comes from your job, Facebook or Twitter comes to your mind. Well, the social networks that we use so much are information systems as well. But, what is an information system? Currently an information system is a set of elements such as people, hardware, software, procedures and data that work together to automate business or daily life processes. For example, in a social network, users could be you and your friends or acquaintances. There are also people in charge of data and they are responsible that your profile is always available. There is possibly a network of computers that contain those profiles all around the world. There is also software that is responsible for updating your status is closing your personal memes. It's important to know that there are two principal types of information systems. Online Transaction Processing, OLTP systems, and Online Analytical Processing Systems, OLAP systems. In the first place, we need to define what a transaction is. A transaction is a set of instructions or operations that are executed on the database all completely or none at all. A transactional information system is the one that serves automate many operations of insert, delete or update data that are performed by many people everyday, all the time. If they were not automated, the process would be very slow. For example, a bank ATM or go shopping. As OLTP systems modify data, there are four properties that should be taken into account to avoid problems in data. The ACID properties. OLTP systems contain a lot of transactions. Each transaction must obey the ACID properties. ACID stands for Atomicity, Consistency, Isolation, Durability. Atomicity, every insert, update, delete data process must be currently executed. If everything was fine, then all changes are reflected to the database COMMIT. In case of any failure none of these processes are reflected to the database, also called roll back. Consistency is a transaction that shall start from a consistent state of the database and in most great and new and valid states of data. Isolation, a transaction in process or running and not yet committed, most remain isolated from any other transaction. In other words, a running transaction must not read any other running transaction data. Durability, where committed data must be persistent. These committed data are stored on physical disk thereby even in the event of a failure and the system restarts, the data will be available and consistent. We will learn what an OLAP system is. The analytical systems on the other hand use information generated in the transactional systems to analyze data and make decisions. For example, based on the ticket of Duke porches in the supermarket and all other people's tickets for months and years, you can analyze which supermarket items are sold together during a certain season. That allows store managers to know what products can be placed on the shelves together or what products should be put on sale depending on their inventory and season. The OLAP systems are used by middle or senior management. The kind of database operations are complex queries of large volume of historical information. If you notice you are in contact with information systems all the time. They have a significant impact on people's lives, organizations, and companies. They can help to automate data and are called transactional systems, or they can analyse data and are called analytical systems. See you on the next video.
