Lesson-1-Introduction-to-Database-Management-Systems.pdf
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Lesson - 1 Introduction to Database Management Systems Mr. Jaymart C. Maala Subject Instructor Topics: I. Database Environment II. The Manual System III. Database Management System Learning Target: Discussed the fundamental concepts of database management systems....
Lesson - 1 Introduction to Database Management Systems Mr. Jaymart C. Maala Subject Instructor Topics: I. Database Environment II. The Manual System III. Database Management System Learning Target: Discussed the fundamental concepts of database management systems. DATABASE ENVIRONMENT DATABASE It is a collection of data organized in a manner that allows access, retrieval, and use of that data. DATA It is a collection of unprocessed items, which can include text, numbers, images, audio, and video. INFORMATION It is processed data; that is, it is organized, meaningful, and useful. INFORMATION It is a facts provided or learned about something or someone. HIERARCHY OF DATA Data is organized in layers. In the computer profession, data is classified in a hierarchy. HIERARCHY OF DATA Each higher level of data consists of one or more items from the lower level. Depending on the application and the user, different terms describe the various levels of the hierarchy. CHARACTER In the American Standard Code for Information Interchange (ASCII) coding scheme, each byte represents a single character, which can be a number, letter, space, punctuation mark, or other symbols. FIELDS It is a combination of one or more related characters or bytes and is the smallest unit of data a user access. FIELDS A field name uniquely identifies each field. The field size defines the maximum number of characters a field can contain. DATA TYPE Specifies the kind of data a field can contain and how the field is used. COMMON DATA TYPES 1. Text 6. Memo 2. Numeric 7. Yes / No 3. Auto Number 8. Hyperlink 4. Currency 9. Object 5. Date 10. Attachment TEXT It also called alphanumeric letters, numbers, or special characters. NUMBER It also numbers only. AUTO NUMBER It is a unique number automatically assigned by the DBMS to each added record CURRENCY It is dollar and cent amounts or numbers containing decimal values. DATE It also called date/time. MONTH HOURS DAY MINUTE YEAR SECONDS MEMO It is lengthy text entries YES / NO It only the values Yes or No (or True or False) HYPERLINK It is an E-mail address or Web address that links to a Web page on the Internet or document on a local network. OBJECT It can be a photo, audio, video, or a document created in other programs and stored as a bitmap in the database. ATTACHMENT It can be a document or image that is attached to the field, which can be opened in the program that created the document or image (functioning similarly to e-mail attachments). RECORDS It is a group of related fields. For example, a student record includes a set of fields about one student. A primary key is a field that uniquely identifies each record in a file. In some tables, the primary key consists of multiple fields called a composite key. FILES It is a collection of related records stored on a storage medium such as a hard disk or optical disc. A database includes a group of related data files. DATA INTEGRITY It is also known as Garbage in, garbage out (GIGO). It is a computing phrase that points out the accuracy of a computer’s output depends on the accuracy of the input. QUALITIES OF VALUABLE INFORMATION 1. Accurate information is error-free. 2. Verifiable information can be proven as correct or incorrect. 3. Timely information has an age suited to its use. 4. Organized information is arranged to suit the needs and requirements of the decision-maker. QUALITIES OF VALUABLE INFORMATION 5. Accessible information is available when the decision-maker needs it. 6. Useful information has meaning to the person who receives it. 7. Cost-effective information should give more value than it costs to produce. ACID properties of database A - Atomicity C - Consistency I - Isolation D - Durability ATOMICITY In database ensures that the transactions are indivisible and irreducible where transactions either commit or abort. CONSISTENCY Any change in the values of a database at a particular instance is consistent with changes to other values. ISOLATION Transaction in database ensures that the working transaction will not be changed or affected by any other transaction. DURABILITY It is the databases states that “once a transaction has been committed, should remain in the same status” even in the case of failures such as Power loss, Database crash, and etc. THE OBJECTIVE OF DBMS Provide for mass storage of relevant data Making easy access to data for the authorized user. Providing a prompt response to user’s requests for data. Eliminate redundantly (Duplicate) the data. THE OBJECTIVE OF DBMS Allow multiple users to be active at one time. Allow the growth of database system Provide data integrity. Protect the data from physical harm and unauthorized access. Serving different types of the users. THE OBJECTIVE OF DBMS Provide security with a user access privilege. Combining interrelated data to generate a report Provide multiple views for the same data. Manual vs Electronic Databases MANUAL DATABASE It is one that is not computerized. ELECTRONIC DATABASE It is one that is computerized and can be accessed/manipulated using computer applications. Advantages of Electronic Databases over Manual databases 1.Electronic databases store very large amounts of data. 2.Electronic databases allow easy input and editing of data. 3.Electronic databases enable automatic updating and recalculating of data. 4.Electronic databases make it easier to query, search, filter, and retrieve required data. 5. Electronic databases format, arrange and present information in customizable ways. 6. Electronic databases can easily share the information with other software applications/programs. 7. Electronic databases allow centralized use of information amongst many users over a network and therefore reduce duplication, e.g in banks. 8. Data is validated before it is entered into electronic databases. Errors created during data entry are minimized 9. Many built-in functions are available in Electronic databases to simplify calculations. 10. Improved security: Database security is the protection of the database from unauthorized users. This may take the form of user names and passwords to identify people authorized to use the database. 11. Economy of scale: Combining all the organization’s operational data into one database, and creating a set of applications that work on this one source of data, can result in cost savings. 12. Increased concurrency: Many DBMSs manage concurrent database access, ensuring that two or more users are allowed to access the same file simultaneously, without interfering with each other, or resulting in loss of information or its integrity. 13. Improved backup and recovery services: modern DBMSs provide facilities to minimize the amount of processing that is lost following a failure. Disadvantages of Electronic Databases as Compared to Manual Databases 1.Complexity 2.Cost of setting up a database 3.The need for conversion & difficult transition 4.Performance 5.Higher impact of a failure Complexity The provision of the functionality we expect of a good database makes it complex to set up. Failure to understand the system can lead to bad design decisions, which can have serious consequences for an organization. Cost of setting up a database The cost of setting up an electronic database varies significantly, depending on the hardware, software, and functionality required. The need for conversion & difficult transition This includes the cost of converting existing applications to run on the new DBMS and hardware plus the cost of training staff to use these new systems, and possibly the employment of specialist staff to help with the conversion and running of the system. Performance It is a file-based system is written for a specific application, such as invoicing. As a result, performance is generally very good. The DBMS is written to be more general, to cater to many applications rather than just one. The effect is that some applications may not run as fast as they used to. Higher impact of a failure The centralization of resources increases the vulnerability of the system. Since all users and applications rely on the availability of the DBMS, the failure of certain components can bring all operations to a halt. DATABASE MANAGEMENT SYSTEM DATABASE MANAGEMENT SYSTEM It is a software program used to create and manage an electronic database. It provides users with tools used to add, delete, access, modify, and analyze data stored in one location. FEATURES OF DBMS 1. Logical Data structures / Objects – such as tables, forms, queries, and reports, used to store and manipulate structured data. 2. A query language (such as SQL) is used to manipulate or extract data. 3. Filter Commands- that display data which satisfy certain conditions. 4. Data validation commands: that ensure the integrity of data entered and stored in the database. 5. Relationships/associations between data objects/ tables. 6. Sort commands/tools that arrange data values in a certain order. 7. Import/Export commands enable sharing of data between the database program and other programs that use similarly structured data. 8. Built-in functions (similar to those available in spreadsheet applications) that simply calculate.
