Database Flashcards
What is manual database?
Documenting data by hand
What is electronic database?
Documenting data on an electronic medium
What is database needed for?
To save and retrieve large amounts of data efficiently
What are the advantages of a database?
More efficient in retrieving information Easy to obtain copies Less physical space required Data analysis can be done more efficiently Data can be shared Independence of data
What are the features of database? (6)
Minimal data redundancy Data consistency Increases efficiency Increases accuracy Increases validity Security
What is data redundancy?
The same data being stored in different tables (enables the maintenance of data consistency)
What are the differences between electronic and manual databases?
(Page 256)
How is a relational data base introduced?
A collection of fields related to one person or object is called a record
A collection of records is called a database
A collection of related tables is called a relational table
What is a primary key?
A column which enables to identify a record uniquely
What is a composite primary key?
The primary key which consists of two or more columns of a table uniquely identified as a record
What is a foreign key?
A field of one table which is used to uniquely identify rows of another table
What are the special features of a foreign table? (3)
Builds a connection between two tables
The related data of the primary key field exists in the other table
Foreign key of one table is the primary key of the other
What are the disadvantages of data duplication? (7)
Inability to select a primary key field Inability to analyse data properly Reduced efficiency Possibility of inaccurate data is high Difficult to enter data Possibility of making errors in deleting data Difficulty of updating data
What is a data type?
A type of data related to one field
What are the different types of data? (5)
Numeric Text Currency Date/Time Boolean (True/False)
What is a Database Management System? (DBMS)
A collection of objects which facilitates planning and maintenance of a database
(Consists of several objects such as tables, queries, forms and reports)
What are some examples of DBMS software? (3)
Access (Microsoft Company)
Base (The Document Foundation)
Oracle (Oracle Corporation)
What is the process of using a DBMS? (4)
Starting the DBMS software
Planing a data table
Creating the primary key
Entering data
What are the different types of relations that can exist among tables? (3)
One-one
One-many
Many-many
What is a one-one relationship?
When only a row of a table is related to a row of another table
What is a one-many relationship?
When each record of a table is related to several records of the other table
What is a many-many relationship?
When a record of a table is related to several records of another table and if a record of that related table is related to several records of the other table
