C03 Flashcards
(30 cards)
Metadata:
Data (raw facts) that describes data (raw facts).
Metadata is data that describes other data. It is information that provides context for the data it is associated with, such as the date a file was created, the author of a document, or the title of a song.
Big data:
Very large and complex sets of data that are difficult to process and analyze using traditional data processing tools.
Database: + Database & Software
A database is a structured collection of data that is stored and organized in a way that allows for efficient retrieval, manipulation, and management of the data. Stores, organizes and manages lots of data.
Databases can be created for specific things, like a structured collection of sales data.
Software must be used to read, store, change, add or remove data from the database.
Database Management System (DBMS):
A software system that is used to interact with (create and change) and manage databases.
Provides an interface to the database and a set of tools to create, modify, and maintain the database, as well as control access to the data.
Database Management System: Relational Data Model
A type of DBMS that organizes data in tables with rows and columns, and uses a specific language, SQL (Structured Query Language), to interact with the data.
Data is organized into separate tables, each with a unique name and a set of columns. Data in different tables are easily related through the use of keys.
Allows lots of information to be stored and a way where they can be related to one another.
Flat file database:
Has one file/table with no relationships. Looks like a spreadsheet.
Database: Definition from Slides
A collection of tables plus their relationships plus metadata (which describes the structure of the database).
Relational Database: Tables/ ( ), ( )/ Column, ( )/ Row, Primary Key, Foreign Key.
- Table/ Relation
- Field/ column = data type.
- Record/ row = each object.
- Primary key = Unique identifier for each record/ row/ object. Needs to have all values present.
- Foreign key: Represents the relationship of other objects with the “main objects.” Data values can be empty/ null.
Composite primary key:
Two columns in a data table represents a unique identifier.
Scale
This means that a database is getting bigger and bigger, being distributed to more computers via network.
Data Hierarchy:
Bit
Bytes: Groups of bites.
Fields (columns): Groups of bytes (columns).
Records (rows): Groups of fields.
Files/ Tables: Groups of records (rows).
Database: Groups of tables.
Composite primary key
Adding up two fields (columns) so that their values together are unique.
Entity
The “topic” of the table. The data contained in the database shown through the “titles of the information.”
Entity Relationship Diagram (ERD):
Visual representation of the structure of the database. It helps design databases.
Schema:
Provides a general description of the database presented by an ERD.
Normalization:
Organizing data in a database such that data is not redundant and that data is honest (consistent and the data is where it needs to be).
The goal of normalization is to reduce data redundancy and improve data integrity by ensuring that data is stored in only one place and is referenced by other tables as needed.
Database manipulation:
The process of adding, changing or deleting data in a database by using tools such as SQL (Structured Query Language).
Some common examples of database manipulation include:
Inserting new records into a table
Updating existing records in a table
Deleting records from a table
Retrieving specific data from one or more tables using a SELECT statement
Creating, altering or deleting tables or other database structures
SQL (Structured Query Language):
A language used to interact with databases to add, change or delete data.
QBE (Query-by-Example):
A graphical (query) tool able to retrieve data using visualized demands. Easy to use, generates SQL. Another language for adding, changing or deleting data in a database.
Entity Relationship Diagram: Entities & Attributes
Each entity (which is what we want to keep track of) represents a box, and each entity has attributes (which describes something about the identity).
Attributes that are part of many entities should become their own entities.
Relationships:
Link between entities.
Cardinality:
Types of relationships between entities.
Cardinalities represent business rules.
Cardinality: One-to-One
Each entity in a relationship has only one related entity between them.
Cardinality: One-to-Many (1:M):
One entity has many related entities and the other in the relationship only has one related entity.
