The Relational Database Flashcards
What is a database
A database is an organized collection of data used for the purpose of modeling some type of organization or organizational process
What are the two kinds of databases
The two kinds of databases are operational databases and analytical databases
What is OLTP
OLTP means online transaction processing
What kind of databases are used in OLTP
Operational databases are used in online transaction processing
What is an operational database for?
operational database is dynamic. It changes constantly. It always reflects up to the minute information. Used when there is need to collect, modify, and maintain data on a daily basis
What is OLAP
OLAP is online analytical processing
What is OLAP used for?
When there is a need to store and track historical and time-dependent data to track trends, view statistical data over time, make tactical or strategic business projections.
What were early database models?
Hierarchical database and network database were early database models
What is a hierarchical database
A hierarchical database is an inverted tree branches flowing from the route
What is the parent child relationship in a hierarchical database
A parent table can be associated with one or more child tables but a single child table can be associated with only one parent table
What is one problem with a hierarchical database?
Users must be very familiar with the structure of the database as users must access data by starting at the route table and working down through the tree to the target data
What are two benefits of a hierarchical database
- the user can retrieve data very quickly because there are explicit links between the table structures
- the referential integrity is built in and automatically enforced the child must be linked automatically to a parent and if the parent is deleted the child will also be deleted
What is another problem with hierarchical databases?
Every item must have a parent, rules cannot be bent without breaking them, every piece of data must be related to another piece of data, it cannot support complex relationships
What is redundant data
Redundant data is when data is entered into two places unnecessarily
What is a network database model
network database model is represented in terms of nodes and set structures
What are nodes?
Nodes represent a collection of records
What are set structures?
Set structures establishes and represents a relationship and the network database
How is set structure different than parent child relationships
Node of owner and node member, transparent instruction relating a pair of nodes together, supports one to many relationship,
How does the owner member structure work
Owner can have many members, but a member can have only one owner, a member cannot exist without a relationship to an owner node
What are set structures
Set structures are the way that data is related to each other, you cannot change a set structure without affecting the application program that use the structure to navigate the data, if you change a set structure, you also change all references from within the application to that structure
Why is a network database better than a hierarchical database?
Fast data access, users can create queries that are more complex, however users must be very familiar with the structure of the database and its set structures
What did Codd believe could be solved in databases by using mathematics?
Data redundancy, week data integrity, database structures over dependence on physical implementation
Relational database model is based on what kind of math?
Relational database model is based on set theory and first order predicate logic
What is a tuple?
A TU PL E is a record or attribute Or field in other words a part of a table
Does the order of the table matter
No the order of the table is imaterial
Why is a relational database an improvement from previous databases
users do not need to know the physical location of a record in order to retrieve its data
What are the categories of relationships in a relational database
121, one too many, and many to many
What does the user of a relational database need to understand
The user needs to be familiar with the relationships among the tables in the database then he can access data and an almost unlimited number of ways
Do tables need to be related in a relational database
No they do not need to be directly related
What is SQL
Structured query language
What is the purpose of structured query language
Structured query language is the process for accessing a relational database. Understanding structured query language will help you to build your queries and understand and troubleshoot your database
What are the four advantages of relational databases?
Built in multilevel integrity, logical and physical data independence From database applications, guaranteed data consistency and accuracy, easy data retrieval
What is multi level integrity
Table level: cannot duplicate records, detect missing key values. Relationship: ensure relationship between a pair of tables is valid. Business: accurate data in terms of the business
What is logical and physical data independence from database applications?
Changing the data will not change the software or the applications that use the data
What is guaranteed data consistency and accuracy?
The integrity of each level creates consistency and accuracy
What is easy data retrieval
Being able to retrieve data from a particular table or any number of related tables easily
Why did relational databases run slowly and how has technology improves
Hardware was unable to keep up with the speed required for databases to reach their full potential but now processing power of computers is cheap and has become an insignificant issue
What is a relational database management system RDBMS
RDBMS is a software application program you use to create, maintain, modify, and manipulate a relational database
What is the client server model of databases
Data resides on server computer and clients interact with the data through an application that resides on their own computers or database client machine. This allows for data integrity and data security on the database server. The client can use the data without affecting the data integrity or security
What is object oriented model
No longer is there a clear separation between the database software and the application programming software. Object-oriented database model has no specific theoretical foundation. There is no cohesive definition
What is OMG?
OMG: object management group a nonprofit international group that addresses the issues of object standards. It is not a standards body such as the American national standards Institute. It is an advisory and certification group
How is OM different than a relational database
OMG allows video clips photographs MP3s to be included in a database
What is a data warehouse?
A data warehouse allows organizations to access data stored in any number of nonrelational databases
