☆ بِسْــــــــــــــمِ اللهِ الرَّحْمَنِ الرَّحِيْـــــمِ ☆
relational database model, the advantages of the relational database model and relational
integrity constraints and business-critical integrity constraints.
Database :
maintains information about various types of objects (inventory), events (transactions), people (employees), and places (warehouse)
Database are divided into three models which is:
- Hierarchical database model - information is organized into a tree-like structure (using parent/child relationship) in such a way that it cannot have too many relationship.
- Relational database model - stores information in the form of logically related two-dimensional tables
- Network database model - a flexible way of representing objects and their relationships.
Entities and Attributes :
- Entities is a person, place, thing, transaction, or event about which information is stored. - the rows, in each table contain the entities.
- Attributes (fields, columns) is characteristics or properties of an entity class. - the columns in each table contain the attributes.
Keys and Relationship :
- Primary key - a field (or group of fields) that uniquely identifies a given entity in a table.
- Foreign key - a primary key of one table that appears an attribute in another table and acts to provide a logical relationship among the two tables.
Relational Database Advantages :
- Increased flexibility - a well-designed database should handle changes quickly and easily and provide users with different view.
- Increased scalability performance - scalability refers to how well a system can adapt to increase demands. And performance is to measures how quickly a system performs a certain process or transaction.
- Reduced information redundancy - redundancy is the duplication of information or storing the same information in multiple places.
- Increased information integrity (quality) - information integrity is to measures the quality of information. And the integrity constraint is the rules that help ensure the quality of information.
- Increased information security - password provides authentication of the user, access level determines who has access to the different types of information, and access control determines types of user access, such as read-only access.
Database Management Systems :
- software through which users and application programs interact with a database.
Database-Driven Websites :
- an interactive website kept constantly updated and relevant to the needs of its customers through the use of a database.
Integrating Information among Multiple Databases :
- Integration is allows separate systems to communicate directly with each other. there has two ways which is forwards integration ( takes information entered into a given system and sends it automatically to all downstream systems and processes.) Then, backward integration and the function is to takes information entered into a given system and sends it automatically to all upstream systems and processes.
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