DBMS Explained PDF

# What is DBMS? A database management system or DBMS is an electronic collection of texts, numeric values, graphs, or images which are systematically processed and stored in computers. A database is a structure that can house information about multiple entity types, as well as relationships among e...

# What is DBMS? A database management system or DBMS is an electronic collection of texts, numeric values, graphs, or images which are systematically processed and stored in computers. A database is a structure that can house information about multiple entity types, as well as relationships among entities. **Source:** http://labs.sogeti.com/wp-content/uploads/2015/08/databases.jpg The DBMS is among the tools that help business environments develop strategic decision making, manage procedures, and process transactions that go in and out of the company. ## Steps Involved in Converting Data to Information | DATA | INFORMATION | | ----------------- | ------------------------ | | ACQUISITION | DISTRIBUTION | | STORAGE | RETRIEVAL | | MANIPULATION | | A DBMS like the student information system enables acquisition, storage, manipulation, retrieval, and distribution of school data. The process is considered a subset of information processing that provides the best evidence of results. - **ACQUISITION** is the process of gathering all the needed information or data, whether it is relevant or not, important or unnecessary. Data can be about the student's profile, subjects, advisers, and grades. This step is very crucial since the quality of data collected will impact heavily on the output (information). This step needs to ensure that the data gathered is both defined and accurate, so that subsequent decisions based on findings are valid. (The decision to be made is based on the output.) - Once acquisition is done, **STORAGE** follows. Data is refined and contained accordingly. The storage, called a table, is allocated to hold the data. For example, a student profile table may include the student number, full name, nickname, birthdate, gender, year level, etc. The subjects enrolled table can have subjects, time, days, rooms, etc. - **MANIPULATION** follows. In this stage, data is analyzed more closely and relationships between these can be established so that viewing and accessing of information can be made possible. This is where "data" is actually converted to "information." This is where you also anticipate queries or questions that may arise. For example, a summary of subjects enrolled or a summary of grades. - **RETRIEVAL** enables you to have a solution or answer to the queries or questions. This stage is where the result of manipulation is retrieved and interpreted to give answer to the queries/questions. - **DISTRIBUTION** pertains to the report that is generated for dissemination. ## STUDENT INFORMATION SYSTEM **Diagram:** A flowchart illustrating the steps involved in a student information system. - The top box reads **STUDENT INFORMATION SYSTEM**. - An arrow points down to a box called **Student's Information**: *Student ID, Full Name, Address, Grades, Adviser, Parents' Name, Parents' Address, Parents' Contract Number, Subjects Enrolled*. - An arrow points down to a box called **Student Registration Form**. - An arrow points down to a box called **Student's Profile (Student's Information)**. - An arrow points down to a box called **Subject Registration (Subject Information)**. - These two boxes point to a box called **List of Students Enrolled**. - An arrow points down to a box called **List of Students per Subject**. - An arrow points down to a box called **Class Schedule**. - On the right side, an arrow points from the **Student's Information** box to a box called **Student's Information (Student ID, Full Name, Course ID, Subject ID)**. - From that same box, an arrow points to a box called **Subject Registration (Student ID, Subject ID)**. - Below both boxes, text reads **SECOND:** Create a storage that will hold the data needed. ## Functions of a DBMS - **Data storage, retrieval and update:** Creates and manages complex structures for data storage, easy data retrieval, and automatic update for every data that is inputted to the workstation. - **A user-accessible catalogue or data dictionary:** Stores definitions of the data elements and their relationships. - **Transaction support (updating):** Allows multiple access coming from different locations. - **Concurrency control services (multiple updating):** Provides data access through query language. - **Recovery services:** Provides backup and data recovery to ensure data safety and integrity. - **Authorization services:** Provides security systems that enforce user security and data privacy by means of security rules. - **Support for data communication and networking:** Supports access of multiple users without compromising the integrity of the database. ## Advantages of DBMS 1. **Controls redundancy:** No data duplication will take place. 2. **Integrity can be enforced:** This means that data in a database is always accurate. 3. **Inconsistency can be avoided:** Propagation of data does not take place. 4. **Data can be shared:** Data can be used and manipulated by multiple users in multiple workstations. 5. **Standards can be enforced:** Elements and procedures are well-defined and carried out. 6. **Restricts unauthorized access:** Security rules determine the table or database that can be used by a particular end user. 7. **Solves enterprise requirements than individual requirements:** The main goal is to have standard requirements for standard procedures. 8. **Provides backup and recovery:** Provides backup and data recovery to ensure data safety. 9. **Cost of developing and maintaining a system is lower.** 10. **Data model can be developed.** 11. **Concurrency control:** Can be accessed by multiple users. ## Disadvantages of DBMS 1. **Complexity:** Different users, different procedures, and business rules are implemented and imposed to the data collection which must be understood and managed by the administrators and end users. 2. **Size:** Requires substantial amount of memory to run efficiently. 3. **Performance:** May not run as fast as it is used to cater to all functionalities being requested to perform. ## Classification of Database Systems The DBMS can be classified based on several criteria: database distribution, users, type of data, and design. ### Classification Based on Database Distribution 1. **Centralized Database:** The database is stored in a single site that is used by several systems. 2. **Distributed Database:** The actual database is distributed from various sites that are connected by a computer network. ### Classification Based on Users 1. **Single user database:** Allows only one connection to a database at a given moment in time. 2. **Multi-user database:** Provides simultaneous access for multiple users. ### Classification of Database Based on Type of Data 1. **Temporal database:** A database with built-in support for handling data involving time. 2. **Data stream Management system database:** A computer program to manage continuous data streams. 3. **Deductive database:** A database system that can make deductions based on the rules and facts stored in the database. 4. **Multimedia database:** Includes one or more primary media types such as text, images, graphic objects (including drawings, sketches, and illustrations), animation sequences, audio, and video. 5. **Spatial database:** Also known as geodatabase, it is a database that is optimized to store and query data that represents objects defined in a geometric space. Most spatial databases will allow representing of simple geometric objects such as points, lines, and polygons. ### Classification of Database Based on Its Design 1. **Flat file database:** Database designed around a single table. It only holds a single table. 2. **Relational database:** Incorporates multiple tables with methods for the tables to work together. The relationships between table data can be collated, merged, and displayed in database forms. ### Elements of a Database - **Entity:** A noun; it is a person, place, or thing. It is represented as a record in a database. - **Attribute:** A property of an entity. It is represented as a field in a database record. - **Relationship:** An association between entities. It is represented using a common field in a set of records. - **Data:** In a list, it is stored in tables. **Diagram:** A diagram showing the relationship between Employee and Department tables. - The diagram illustrates a relationship between two tables: **Employee** and **Department**. There is a relationship between the two called **works**. The relationship is represented by an arrow. - The **Employee table** has the following attributes: `ID Number`, `Name`, `Address`, and `Salary`. - The **Department table** has the following attributes: `Dept Code`, `Name`, and `Location`. ## Examples of Database Applications 1. **POS (point of sale):** A database application commonly used in fast-food restaurants, department stores, or supermarkets. This application records the items or products that go outside the premises, and automatically counts the number of items left in the warehouse. 2. **Mobile/Smartphone contact information system:** A database application used by mobile companies to store a person's contact information such as name, mobile number, email address, and even a picture included with it. 3. **Library information system:** An application used in libraries to determine the number of books available, list of available authors, titles, and a copy of books. 4. **Search engine:** A database application in a web environment that will enable you to search the nearest and most available information you want to obtain. Examples are Google and Dogpile. 5. **Hospital information system** An application used in a hospital facility. It determines whether there is an available room for the patient, the doctor's name and his/her specialization, plus the clinic hours he/she renders in the hospital.