Information Systems and Databases - Summary PDF

**Information Systems (2)** **Business process**: sequence of business activities with the goal to producing a product or performing a services that involves multiple resources: - Material - Organizational - Informational **Information system** = it is a set of information managed by busi...

**Information Systems (2)** **Business process**: sequence of business activities with the goal to producing a product or performing a services that involves multiple resources: - Material - Organizational - Informational **Information system** = it is a set of information managed by business processes - **Data assets**: raw material with which information is produced - **Set of procedures** : for information acquisition, processing, production - **Set of human ressources**: oversee the procedures - **Set of tools and instruments:** storage and processing of information Information system: set of components of an organization to : - store, - share, - process - acquire - retrieve (zurrückholen) - transmit **Components of an information system:** - Human ressources - Automated and non automated tools - Automated and non automated procedures - Data assets **Computer system**: a computer system is the technology supporting the information system - Hardware - Software - Databases and management systems - Communication networks Companyorganizationinformation system (people, employees, major)computer system (automatic management) Information production: Events Acquisition data data processingdatatransmission (übertragung)informationrecipients (Empfänger)update data **Example of an information and computer system:** Municipality (gemeinde) equipped with information and computer system for detecting the level of smog: - Information system: people (employees, mayor...), methods and procedures for the production and management of information that is related to pollution - Computer system: **automatic management** by appropriate staff of smog level information using: **hardware machines, software programs and network equipment** **Computer systems** need information technology to process data and produce information ( these procedures are automated and consist of programs running on a computer Information of an organization is available in the form of a set of data stored on media. This kind of data needs to be interpreted to give rise to the actual information **Data** is a representation of information useful for its storage and management. **Raw data and the rules for their interpretation are stored** in the form of data **Elementary information:** - Attribute (customer, date of birth, book title) - Type (string, date) - Value (paolo rossi, the actual date of birth...) Ein Bild, das Text, Screenshot, Schrift, Reihe enthält. KI-generierte Inhalte können fehlerhaft sein. **Complex information:** Elementary information is logically related to each other this results in complex information. Data Information complex information  **Different interactions with databases:** - Shopping - Purchases with credit cards - Payment of insurance - Enrolling in a course Require: Use of data collections, that are: - stored persistently(andauernd) - related to a reality of interest - serving a given organization **Database:** A database is a set of information associated with a collection of data: - Related to each other - Equipped with an appropriate description **A database is:** - A single large data repository (Archiv, Verzeichnis) - Shared within the enterprise by all applications and users - Persistent (andauernd) - A tool that allows you to work on a consistent state of data. **Database description:** - The database must maintain its own description (beibehalten) - This refers to a catalog containing a set of data called metadata that is used to describe the data itself - All this is achieved through a software layer called DBMS, that manages all data, ensuring that operations are carried out efficiently and effectively **DBMS is a set of programs which allows you to** - Define: specify types, structures and constraints on data - Manipulate: Insert, delete, update, retrieve data - Check: controll access to data, ensuring protection from failures A DBMS makes it easier for users to use their database. Before DBMS a data store consisted of a set of files and all operations and information management logic were the responsibility of the applications that interacted with the store With DBMS applications that interact with the database are simplified For example managing a phone book: You have to registrate names of friend with addresses, phone numbers, cell phone numbers... Personal approach: - You manage it with appropriate programs written in the preferred language. Approach using DBMS: - A DBMS product is used. It allows data definition and management by SELECT, INSERT, DELELTE, UPDATE operations **Database system:** A database system is the set formed by a database and DMBS Ein Bild, das Text, Screenshot, Diagramm, Schrift enthält. KI-generierte Inhalte können fehlerhaft sein. **Anti Sparc Three Level Architecture** Basic purpose was to ensure strict isolation between the data and the programs/applications that operate on them. **It helps to achieve data independence by separating the database into 3 levels** A database always has a single conceptual schema and a single physical schema Dividing different levels which are relevant in the usage of data  **External level** - describes the views of the user of the data - different users can have different views of the same data - provides security by restricting access **Conceptual level** - describes the logical organization of data - defines tables, relations, constraints - ensures logical independence Ein Bild, das Text, Screenshot, Schrift, Diagramm enthält. Automatisch generierte Beschreibung **Internal level** - describes how data actually is saved on physical storage media - ensures physical data independence All of this results in a databse  **Data independence:** - **Logical Data Independence** -- You can change the structure of the database (like adding a new column) without changing the programs. - **Physical Data Independence** -- You can change how data is stored (like using a different storage method) without changing the database structure. **External schema example:** How a specific user or application sees the data in a database An external schema can be designed to provide different views of the data for different users - Users only see the data that they need Ein Bild, das Diagramm, Reihe, Design enthält. KI-generierte Inhalte können fehlerhaft sein. **Easy Example of ANSI-SPARC Three-Level Architecture** Online Library System as an example. **External Level (User View)** Different users see different parts of the data: - Students can see book titles, authors, and availability. - Librarians can see student records, book loans, and due dates. - Admins can access everything, including system settings. **Conceptual Level (Logical Structure)** Defines the database structure: - Tables: Books, Users, Loans - Relationships: - Each book has an ID, title, author, and availability. - Each user has a User ID and borrowing history. - Loans connect users to borrowed books with due dates. **Internal Level (Physical Storage)** Manages how data is stored on disk: - Uses indexes for fast searching. - Data is stored in binary format for efficiency. - Optimized file storage techniques reduce space usage. **History of DBMS** - Hierarchical model 1960s: data organized into hierarchies - Reticular model 1970s: data organized in a lattice through the use of graph data structures - Relational model implemented late 1970s**: data organized in relationships, that is a set of records having the same structure** **Object oriented model**: data is organized in the form of software objects and links between them purely object oriented no tables **Object relational model:** model remains relational but the table structure is generalized in order to contain objects as well as elementary values supports also tables mix of relational(tables) and object oriented features **Not only SQL models (NoSQL):** **Functionality of DBMS:** - **defining** how data are organized into information through data definition language (DDL) - **query (abfragen) and manage data** through DML (Data manipulation language), INSERT, UPDATE, DELETE  **DBMS** excecutes particular programs called transactions: - **A transaction** is the **execution** of a user program in **a DBMS** environment. - Either ends in a program expected end state **(commit)** or takes the system to the state before the **transaction began (abort)** **Operations in transactions:** - SELECT - INSERT: to insert a new object into the database - UPDATE: to modify pre existing object in the database - DELETE: to delete an object within the database **Acid properties(Eigenschaften) of transactions:** - **Atomicity**: all or nothing property, a transaction is atomic if it is executed in its entirely (vollständig) or not at all (gar nicht) - **Consistency :** a transaction is a transformation of one consistent state of the database to another consistent state. DBMS must ensure that all constraints defined on the database are satisfied - **Isolation:** Transactions must be executed independently of each other - **Durability:** the effects of a transaction that is terminated(beendet)by a commit must be permanently recorded in the database and never lost for any reason **Features of a DBMS:** - **[Redundancy (Überflüssigkeit) and consistency check]**a DB based approach tends to eliminate unnecessary duplication (redundancy) of datathis reduced the risk of inconsistencyif a data item is available only once in the Database, a change is immediately available to all - [**Sharing**:] organizations data is shared by all users and applications in an organization - [**Data Integrity:**] we have DBMS handle changes in the information through appropriate constraint rules - [**Efficient management of operations**:] DBMS has features for efficient execution of queries and updates - **Concurrency control**: DBMS guarantees concurrent (simultan) transactions on the data without interference (Beeinflussing) - **Reliability:** DBMS has functionality for restoring databases even in case of failures or malfunctions during transaction execution - **Security:** prevention from data access by unauthorized users **Main components of DBMS**: - **Access Manager**: module that performs data access control. Ensures that only authorized users and applications have access to information in the database - **Query Manager**: component that handles users request in terms of DDL and DML operations. Translates DDL and DML commands into an internal DBMS format - **Memory Manager**: component that is responsible for defining strategies for accessing information in mass memory and its transfer to central memory - **File Manage**r: module that deals with the management of files on mass Storages (Datenspeicher, die große Mengen an Daten dauerhaft speichern können) - **Integrity Manager:** module that is responsible for verifying that integrity rules are verified within the database - **Concurrency control manager**: module that aims to manage concurrent transactions to access shared database resources. - **Reliability manager**: module that dals with saving operations **Examples of information systems (3)** **Operational support systems: managing information changes** - Withing operational processes (Business to Business) - Between processes in the same company - Between user and company (Business to Consumers) **Typical functions:** - Management of business strategies - Processing business transactions - Planning and control of operations - Management of administrative procedures **Information handled by these processes are:** - Biographical information (describes structural properties of objects and actors of the system - Information on transactions (describe events, movements of resources of both economic and financial and material nature) - Information on operations planning ( describe the production plan of a given organization Such information can be - Stable over time (customer supplier and product master records) - Changeable over time (current account balance) - Related to events (describing business transactions, such as airline, hotel, cat reservations [Management of orders and purchases] - **Information acquisition** (sales office employees acquire daily customer orders) - **Information storage** (order information is entered via terminals within the system and in stored in a special central server - **Information processing** (the information is then processed and analyzed by purchasing department employees) - **Information communication** (based on remaining quantities in the warehouse the procurement manager can decide whether or not the order can be fulfilled. The information systems consists of the total sets of people (employees, manager etc), means and procedures necessary for the production and management of information related to the purchasing and sales processes. The computer system concerns(angehen) that subsets dedicated to the automatic management of information by means of hardware machines, software programs and network equipment. Depending on the remaining quantity in the warehouse the manager can choose wither to issue a new order to suppliers with the aim of minimizing the cost of stocking sold Monitoring and control systems: - Environmental monitoring (detecting fires in forests, monitoring a city's smog level) - Monitoring of structures (detection and location of damage to buildings or bridges) - Surveillance (video surveillance systems) - Controlling the flow of goods and products - Medical applications - Access control - Detection and control of traffic flow - Public transportation **Environmental monitoring systems:** - Control units and sensors, daily detect and acquire the smog values **(information acquisition)** - Data sent to a special communication network to a server that stores them into special databases **(information storage)** - Data is then using special software programs, processed and analyzed by employees (**information processing)** - Results of daily data analysis are presented to the major **(information communication)** This analysis impacts the decision making of the municipality **Video Surveillance Systems:** - Cameras continuously acquire information about the observed scene **(information acquisition)** - Data is sent to a central processor or server that stores it in archives (**information storage)** - Data is processed in real time by special software programs **(information processing)** - If anomalies detected operators can check for the actual presence of unnormal things and report alarm to security managers or someone else**. (information communication)** **Information systems in public administration** - Ministry of agriculture and forestry - National health informations system - Public education system - Ministry of justice **Document management** An important aspect to highlight is the document management. - Presents problems and critical issues of an organizational, technological and archival nature. - It consists of the set of documents produced and acquired for institutional purposes of an agency or administration. **Macro objectives to achieve with a document management:** - Production/acquisition of reliable documents for legal and administrative purposes - Intake and processing of documents - Organization and maintenance of documentary production - Transmission and preservation of authentic documents - The speed and efficiency of retrieval (Abfrage) **Hospital information systems** A hospital information system is an integrated information system designed to manage all aspects of a hospital (administrative, financial, clinical, medical, research). Usually this kind of information system is divided into subsystems related to various medical areas. Other examples: - Transportation information systems - Airport **Introduction to R (3)** R is an integrated suite (reihe von) of software facilities for - Data manipulation - Calculation - Graphical display It has also - Data handling and storage facility - Operators for Calculation on arrays (Reihen) - Tools for data analysis - Graphical facilities for data analysis and display - Well developed and simple, effective programming language - Fully planned and coherent (einheitlich) system - Methods for interactive data analysis - Large collection of packages A question mark will display a functions help text (alternative for the help function) \#This is an R comment The rm command removes variables Install.packages ()this goes to CRAN looks for packages with the name you typed in and downloads it to your computer When R is running variables, data, functions, results are stored in the active memory of the computer in the form of objects a \