A Database is a collection of records.
Multidimensional Databases (e.g., Relational Databases):
Structure: These databases are organized in a way that allows them to represent multiple dimensions or aspects of the data. Access: Information can be accessed and viewed from various perspectives. Internal Linking: Entries in the database are often linked internally, allowing for complex queries and relationships between different data elements. Example: A relational database where you can view data in various ways, such as by customer, by product, or by date, and see the relationships between these entities. Traditional Flat File Systems:
Structure: These systems are one-dimensional, meaning they have a simpler, flat structure. Access: Information is presented from a single perspective or point of view. Lack of Interaction: Traditional files generally do not interact or link with other files, limiting the way data can be correlated or analyzed. Example: A simple spreadsheet or text document where data is listed in rows and columns, but without the ability to easily link or relate this data to other files or datasets. In summary, multidimensional databases offer a more flexible and interconnected way of storing and accessing data, allowing for complex data relationships and queries. In contrast, traditional flat file systems are simpler and more limited in how data is organized and accessed, usually not supporting intricate data relationships.
Database Management Systems
Typical Database Application Layers:
Function: This layer communicates directly with the end user. Complexity: Can be fairly complex, depending on the application. Example: When users access a database via a website, this layer includes programs and services on a server. These components handle user requests, process them, and then interact with the database management layer. Database Management Layer:
Role: Responsible for managing the actual database. Interaction with Application Layer: It receives queries from the application layer (e.g., server programs), executes these queries on the database, and returns the results. Behind-the-Scenes Work: This layer handles the storage, retrieval, and updating of data in the database. In essence, the application layer acts as the interface between the end user and the database, managing user interactions, while the database management layer focuses on direct database manipulation and maintenance.
Types of Databases
Flat-File Database
Structure: Consists of a single, flat file or table. Simplicity: Very simple and straightforward, with data typically organized in rows and columns. Limitations: Limited in terms of handling large volumes of data or complex data relationships. Relational Database
Structure: Organizes data into tables which can be linked by defined relationships. Flexibility: Allows for complex querying and data manipulation. Popular Use: Widely used in various applications due to its versatility and scalability. Think of it like a school locker system. Each locker (or table) holds different things (data), like books in one, sports equipment in another. If you need to put together your backpack for the day, you go to different lockers and pick what you need. This is like the database getting data from different tables. The lockers are organized in rows and columns, and you can easily find what you need by knowing which locker and which shelf to check. Hierarchical Database
Structure: Data is organized in a tree-like structure, similar to a file system hierarchy. Parent-Child Relationship: Each record has a single parent but can have multiple children. Use Cases: Useful in scenarios where data relationships are inherently hierarchical, like organizational structures or file systems. Object-Oriented Database
Structure: Stores data in the form of objects, as used in object-oriented programming. Integration: Seamlessly integrates with object-oriented programming languages. Advantages: Ideal for applications that require complex data manipulation and storage of data as objects (like multimedia elements and complex data structures). Imagine you have a backpack that keeps everything you need for school – your books, lunch, and sports gear. Everything is in one place and organized in a way that makes sense for you. In this backpack, things are not just thrown in; they are in small bags or containers (objects) that group similar items together, like a lunch box or a pencil case. So, when you need something, you grab the whole container that has everything related. This is like an object-oriented database, where data is grouped in objects, and each object has its own related information.
6.1 Intro to management of Databases
