Introduction to Database Management Systems: Structure, Applications, and Key Benefits
3 likes21,360 views
A Database Management System (DBMS) is a program that allows for easy access, management, and updating of organized data, providing several benefits such as flexible data access, improved integrity, and reduced redundancy. Different data models exist, including hierarchical, network, relational, and object databases, each with its own structure and advantages. Additionally, SQL is the query language used to interact with databases, enabling users to retrieve and manipulate data effectively.
Introduction to Database Management Systems: Structure, Applications, and Key Benefits
- 2. INTRODUCTION TO DATABASES A database is a collection of data organized to serve many application. By using centralized data it can easily be accessed, managed, and updated. And a DATABASE MANAGEMENT SYSTEM (DBMS) is a collection of programs that enables you to store, modify, and extract information from a database.
- 3. ADVANTAGES OF USING A DATABASE APPROACH • Flexible Data Access. • Improved Data Integrity (purity,). • Improved Data Security. • Data Independence. • Reduced Data Redundancy (excess). • Ability to Share and Relate Data • Standardisation of Data. • Increased Productivity.
- 5. DBMS and Its Applications: A DATABASE MANAGEMENT SYSTEM (DBMS) is a computerized record-keeping system. It is a repository or a container for collection of computerized data files. Application are as follows: – Banking – Airlines – Universities – Manufacturing and selling – Human resources – Railway reservation system – Library management system – Social media sites – Telecommunications – Online shopping – Human resource management
- 6. ELEMENT OF DATABASE FIELDS: A field is part of a record and contains a single piece of data for the subject of the record. In the database table illustrated in Figure 4, each record contains four fields:
- 7. RECORDS: Data is stored in records. A record is composed of fields and contains all the data about one particular person, company, or item in a database. In this database, a record contains the data for one customer support incident report. Records appear as rows in the database table. A record for Log ID 1201242 is highlighted in Below mentioned Figure.
- 8. TABLES: A database table is composed of records and fields that hold data. Tables are also called datasheets. Each table in a database holds data about a different, but related, subject.
- 9. An Example of a Table Records Fields Name GatorLink Phone College Graff rgraff 392-3900 Pharmacy Harris bharris 392-5555 Medicine Ipswich zipswich 846-5656 PHHP
- 10. KEY FIELD: A field of a database (typically a relational database ) table which together form a unique identifier for a record (a table entry). The aggregate of these fields is usually referred to simply as "the key ".
- 11. PRIMARY KEY • The column or set of columns that provide the uniqueness for the row. • A table can have only one primary key. • Existing values in primary key columns may not be modified (insert new value and then delete old value) • The table of a relationship containing the primary key is called the Parent Table.
- 12. FOREIGN KEYS • A primary key referenced from another table is called a foreign key • For each foreign key value, there must be a row in a table whose primary key has the same value. • The foreign key can be made up of one or more columns of a table but must match the primary key it is referencing • A table can have any number of foreign keys.
- 13. PRIMARY KEYS & FOREIGN KEYS Name User Phone College Graff rgraff 392-3900 Pharmacy Harris bharris 392-5555 Medicine Ipswich zipswich 846-5656 PHHP To ensure that each record is unique in each table, we can set one field to be a Primary Key field. A Primary Key is a field that that will contain no duplicates and no blank values. Foreign Keys link to data in other tables
- 14. DATA MODELS 1. HIERARCHICAL 2. NETWORK 3. RELATIONAL 4. OBJECT
- 15. 1. HIERARCHICAL MODEL Stores data as hierarchically related to each other. Record shape are tree structure. BUET Faculty of Civil Engineering Faculty of Architectural CE WRE URP Archit.
- 17. HIERARCHICAL DATABASE MODEL • Logically represented by an upside down tree – Each parent can have many children – Each child has only one parent
- 18. HIERARCHICAL MODEL • Several records or files are hierarchically related with each other. For example, an organization has several departments, each of which has attributes such as name of director, number of staffs, annual products etc. • Each department has several divisions with attributes of name of manager, number of staffs, annual products etc. • Then each division has several sections with attributes such as name of head, number of staff, number of PCs etc.
- 19. Advantage and Disadvantages of Hierarchical Model Advantages High speed access to large databases Easy to update- (to add or delete new nodes) Disadvantages Links are only possible in Vertical Direction (from top to bottom) but not for horizontal or diagonal unless they have same parents. For example, it is hard to find what is the relation between URP and DCE from this data model.
- 20. 2. NETWORK DATABASE MODEL • Doesn’t force data into hierarchical levels • Owner/Member relationships: – Owner record type – Member record type • Each owner may have one or more member types • Each member type and corresponding owner record type form set, which represents relationship
- 22. Network Database Model • Each record can have multiple parents – Composed of sets - relationships – Each set has owner record and member record – Member may have several owners – A set represents a 1:M relationship between the owner and the member Figure 1.10
- 23. 3. RELATIONAL MODEL • Based on two important concepts: – Key of relation - one to one, one to many, many to many – Primary attribute – which can’t be duplicate Student ID Name CourseID 1 Mr. X 001 2 Mr. X 002 3 Mr. Y 003 Cour seID Title Cre dit 001 RS & GIS in WM 3 002 Watershed Hydrology 3 003 Risk Management 3 Course table Student Table Student Table Course Table * * Many to many relationship
- 24. WHAT IS A RELATIONAL DATABASE? • A database is more than just a collection of information. Such as student and course information, faculty and grades. • A database is a representation of the people and things your business needs to operate, and the way those people and things relate to each other. • A database system supports the business rules defined by the customer.
- 25. RELATIONSHIP TYPES 1. One-to-One : relationship is single valued in both directions. A manager manages one department; a department has only one manager. 2. One-to-Many : relationship is multi-valued in one direction - one row in the parent table is associated with many rows in the dependent table. One department has many employees. 3. Many-to-Many : relationships are multi-valued in both directions. This type of relationship can be expressed in a table with a column for each entity. (crosswalk table) - An employee can work on more than one project, and a project can have more than one employee assigned. Employee, Project, and Employee/Project tables.
- 27. Relational Database Model Figure 1.11
- 28. WHAT IS QUERY LANGUAGE? • Query language (QL) refers to any computer programming language that requests and retrieves data from database and information systems by sending queries.
- 29. WHAT IS QUERY ? A query is a request for information from a database.
- 30. SQL What is it? Structured Query Language • Used in ORACLE and other DB systems • Non-procedural - i.e. Specify what you want not how to get it • SQL - (also pronounced SEQUEL) directly related to the development of the RELATIONAL MODEL by E.F.Codd.
- 31. SQL • SQL is used to perform query in relations databases. • For example, find the name of the student who took more than or equal to 6 credit hour in this term SELECT Student.Name, Course.Credit FROM Student, Course WHERE Student.CourseID = Course.CourseID AND Credit >= 6 • The answer is : Mr. X 6
- 32. Find the relationship between this two tables in the BUET Library ISBN Title Author 050 Applied Hydrology David Maidmen 060 Irrigation Cheng ID Name ISBN 1 Mr. P 050 2 Mr. Q 060 3 Mr. R 070 Book Table Borrow Table One to one Many to Many One to Many ?
- 33. Advantage of Relational Database Advantages there is no redundancy. type of building of an owner can be changed without destroying the relation between type and rate. a new type of building for example "Clay" can be inserted. (row insert is easy). Disadvantages Require a number of tables and relationship Its difficult to add a new column in the table.
- 34. 4. OBJECT DATABASES • Current generation systems have a need to handle complex data for complex applications such as – computer aided design – computer aided software engineering – geographic information systems – interactive web sites • Relational systems are inadequate for these systems – Why do you think this is?
- 35. Object Database Types • Object-oriented – extend a programming language such as Java with persistency and a query language • Object-relational – extend a current RDBMS (e.g. Oracle) with object- oriented extensions
- 36. Object Oriented Model BUET Departments Institutes CE WRE DCE IWFM URP AIT Faculty, Staff, Students Attributes: Is a Is a Is a Is a = Inheritance Part of = association Part of Part of
- 37. OBJECT ORIENTED DATABASE • An Object Oriented model uses functions to model spatial and non- spatial relationships of geographic objects and the attributes. • An object is an encapsulated unit which is characterized by attributes, a set of orientations and rules. An object oriented model has the following characteristics. • GENERIC PROPERTIES : there should be an inheritance relationship. • ABSTRACTION : objects, classes and super classes are to be generated by classification, generalization, association and aggregation. • ADHOC QUERIES : users can order spatial operations to obtain spatial relationships of geographic objects using a special language.