INTRODUCTION TO DATABASE USING MS ACCESS 2013 PART 2 NOVEMBER 4, 2014

WHAT IS DATABASE? a structured set of data held in a computer, especially one that is accessible in various ways. a structured set of data held in a computer, especially one that is accessible in various ways. an organized collection of data. an organized collection of data. a collection of data that is organized so that its contents can easily be accessed, managed, and updated. a collection of data that is organized so that its contents can easily be accessed, managed, and updated.

TWO MAIN TYPES OF DATABASE

OPERATIONAL DATABASE It is a dynamic database that is used by any organization in its daily operation. They are used to collect data, maintain, modify and delete data. It is a dynamic database that is used by any organization in its daily operation. They are used to collect data, maintain, modify and delete data.

ANALYTICAL DATABASE It is a static database, wherein data is rarely modified. This database is often used and track historical data to make long term projections and analysis. It is a static database, wherein data is rarely modified. This database is often used and track historical data to make long term projections and analysis.

SIX STRUCTURED DATABASE MODELS

ENTITY-RELATIONSHIP MODEL This model is an abstract conceptual representation of data. This model is an abstract conceptual representation of data.

HIERARCHICAL MODEL In a hierarchical model, data is organized into a tree-like structure, implying a single parent for each record. A sort field keeps sibling records in a particular order. Hierarchical structures were widely used in the early mainframe database management systems, such as the Information Management System (IMS) by IBM, and now describe the structure of XML documents. This structure allows one one-to-many relationship between two types of data. This structure is very efficient to describe many relationships in the real world; recipes, table of contents, ordering of paragraphs/verses, any nested and sorted information. In a hierarchical model, data is organized into a tree-like structure, implying a single parent for each record. A sort field keeps sibling records in a particular order. Hierarchical structures were widely used in the early mainframe database management systems, such as the Information Management System (IMS) by IBM, and now describe the structure of XML documents. This structure allows one one-to-many relationship between two types of data. This structure is very efficient to describe many relationships in the real world; recipes, table of contents, ordering of paragraphs/verses, any nested and sorted information.

NETWORK MODEL The network model expands upon the hierarchical structure, allowing many-to- many relationships in a tree-like structure that allows multiple parents. It was most popular before being replaced by the relational model, and is defined by the CODASYL specification. The network model expands upon the hierarchical structure, allowing many-to- many relationships in a tree-like structure that allows multiple parents. It was most popular before being replaced by the relational model, and is defined by the CODASYL specification.

DIMENSIONAL MODEL In the dimensional model, a database schema consists of a single large table of facts that are described using dimensions and measures. A dimension provides the context of a fact (such as who participated, when and where it happened, and its type) and is used in queries to group related facts together. Dimensions tend to be discrete and are often hierarchical; for example, the location might include the building, state, and country. A measure is a quantity describing the fact, such as revenue. It is important that measures can be meaningfully aggregated—for example, the revenue from different locations can be added together. In the dimensional model, a database schema consists of a single large table of facts that are described using dimensions and measures. A dimension provides the context of a fact (such as who participated, when and where it happened, and its type) and is used in queries to group related facts together. Dimensions tend to be discrete and are often hierarchical; for example, the location might include the building, state, and country. A measure is a quantity describing the fact, such as revenue. It is important that measures can be meaningfully aggregated—for example, the revenue from different locations can be added together.

OBJECT-RELATIONAL MODEL Is a model that utilizes the relationship model as well as the object oriented- programming paradigm. This model attempts to bring database and application programming closer together. Is a model that utilizes the relationship model as well as the object oriented- programming paradigm. This model attempts to bring database and application programming closer together.

RELATIONAL MODEL The relational model was introduced by E.F. Codd in 1970 as a way to make database management systems more independent of any particular application. It is a mathematical model defined in terms of predicate logic and set theory, and systems implementing it have been used by mainframe, midrange and microcomputer systems. The relational model was introduced by E.F. Codd in 1970 as a way to make database management systems more independent of any particular application. It is a mathematical model defined in terms of predicate logic and set theory, and systems implementing it have been used by mainframe, midrange and microcomputer systems. The products that are generally referred to as relational databases in fact implement a model that is only an approximation to the mathematical model defined by Codd. Three key terms are used extensively in relational database models: relations, attributes, and domains. A relation is a table with columns and rows. The named columns of the relation are called attributes, and the domain is the set of values the attributes are allowed to take. The products that are generally referred to as relational databases in fact implement a model that is only an approximation to the mathematical model defined by Codd. Three key terms are used extensively in relational database models: relations, attributes, and domains. A relation is a table with columns and rows. The named columns of the relation are called attributes, and the domain is the set of values the attributes are allowed to take.

DATABASE DEFINITIONS/TERMINOLOGIES

DEFINITIONS DATA – it is a number or value found and stored in the database. DATA – it is a number or value found and stored in the database. INFORMATION – it is a data that has been processed thereby making it relevant and meaningful to the person viewing it. Information is dynamic because it changes relative to the data stored in the database and it could be processed in many ways. INFORMATION – it is a data that has been processed thereby making it relevant and meaningful to the person viewing it. Information is dynamic because it changes relative to the data stored in the database and it could be processed in many ways. RELATIONSHIPS – they exist when two or more tables have connection or association RELATIONSHIPS – they exist when two or more tables have connection or association

NULL – it is used to represent a value that is unknown or missing. A null value is neither zero nor blank NULL – it is used to represent a value that is unknown or missing. A null value is neither zero nor blank FILE – it is an organized collection of data about an entity. FILE – it is an organized collection of data about an entity. RECORD – it refers to a specific person, place, thing or event. Record also known as the “tuple in the relational database terminology. It pertains to structure in the database table which database table representing unique instance of a subject RECORD – it refers to a specific person, place, thing or event. Record also known as the “tuple in the relational database terminology. It pertains to structure in the database table which database table representing unique instance of a subject

FIELD – it is the smallest structure of a data from a larger database structure in a relational database. A field can store data in database and represent a character of the subject to which database table it resides FIELD – it is the smallest structure of a data from a larger database structure in a relational database. A field can store data in database and represent a character of the subject to which database table it resides VIEW – it is also known as virtual table. It is called a virtual table since it does not hold data on its own; rather it gets data from the table to which it is based. And since it comes from other table it is composed of several fields coming from one or more data. VIEW – it is also known as virtual table. It is called a virtual table since it does not hold data on its own; rather it gets data from the table to which it is based. And since it comes from other table it is composed of several fields coming from one or more data. KEYS – these are field that serve a specific purposed within a table. There are two types of keys, the primary and the foreign key. The primary key is a field that uniquely identifies a record in the table while a foreign key is a special field that establishes relationship between two tables. KEYS – these are field that serve a specific purposed within a table. There are two types of keys, the primary and the foreign key. The primary key is a field that uniquely identifies a record in the table while a foreign key is a special field that establishes relationship between two tables.