B5
– Ronald Herazo
Relational
Database
There are different types
of databases that can be used for different purposes. Nowadays, statistician
use two types of databases: flat and relational databases. A good definition of
relational databases is a database that contains two or more related tables [2].
In order words, a relational database is a database that treats all its data as
a collection of relations; they are usually manipulated a set at a time rather
than a record at a time. This particular database is mainly based on relational
model of data, and it was first proposed by Dr. Codd in 1970. Also, this
specific relational model contains components, such as collection of objects or
relations, set of operations to act on the relations, and data integrity for
accuracy and consistency.
There are multiple
software using relational databases. These software systems are known as a
relational database management system (RDBMS). For instance, EcoLab is a Swedish
Life Cycle Assessment (LCA) program that has been used mainly in the European
industry. One of the main advantages of using this software is its relational
database [4]. Therefore, Relational Database Management System is a software
that can store and updates a relational database. Nowadays, RDBMS has the two-major
software that allow the user to work efficiently (see Figure 1 and 2). Client
Server RDMS is a server software that provides a middleware layer between
client applications and database files. Additionally, Embedded RDMS is
integrated application program where the data is typically stored in a single
file.
Figure 1
-Client-Server RDBMS
Figure 2
- Embedded RDBMS
In relational database, entities
are stored in tables in which each row of a table stores one record and each
column of a table stores one attribute per record. Additionally, the primary
key of a relation is an attribute or set of attributes that exclusively
identifies a record [1]. Therefore, the relationships between entities can be
represented in an Entity-Relationship (ER) diagrams with the purpose of showing
attributes, keys, and relationships. In this diagram, primary key is underlined
(see Figure 3).
Figure 3 -
Entity-Relationship Diagrams
Relational databases have
real world objects that need to be modeled in the database. These real-world
objects are called entities. Within relational databases, entities can be
related to other entities by three different relationships: one-to-one,
one-to-many, and many-to-many. For instance, in a relational database, a
one-to-one relationship exists when one row in a table may be linked with only
one row in another table, and vice-versa [3]. Moreover, a one-to-many
relationship occurs when one row in table X may be linked with many rows in
table Y, but one row in table Y is linked to only one row in table X [1].
Finally, a many-to-many relationship is a relationship between two entities (X
and Y). For example, an author can have
many journals, and a journal can have many authors (see Figure 4).
Figure 4 -
Many-to-many relationships
Finally, the Structured
Query Language (SQL) is used to manipulate relational databases. SQL has four
different languages:
1. Data Definition Language is
typically used when a database is first created with the purpose of creating, modifying,
and deleting database tables.
2. Data Manipulation Control Language
allows the user to inert, update and delete data from tables.
3. Transaction Control Language allows
the user to create transactions.
4. Data Control Language
is mainly used for setting permissions.
References
[1]
Simpkins, Christopher. "Relational Databases." Relational Databases (1986): n. pag. Georgia Institute of Technology. Web. 11 Feb. 2017.
[2]
Telvent. "Relational Database Performance." Relational Databases (1986): 339-59. ArcFMSolution. Web. 11 Feb. 2017.
[3]
Veenstra, Peter. "Relational Database Management Systems." Relational Database Management Systems,
Database Design, and GIS (2009): 3-20. University
of Missouri Columbia. Web. 11 Feb. 2017.
[4]
Andrae, A. S. G. Global Life Cycle Impact
Assessments of Material Shifts: The Example of a Lead-free Electronics Industry.
London: Springer, 2010. 59-62. Print.
Comments:
Egla,
Before this class, I had
no clue about Structured Query Language (SQL). You really did a good job
explaining SQL and the main commands that are used in this software. One thing I
know is that the Structured Query Language (SQL) is used to manipulate
relational databases. But, I did not have a chance to read more about it. However,
I like when you highlighted on your post that “Learning SQL is important
because it gives the user the power to access and interpret data, especially in
the programming/developing sphere." As an engineer, I think this software
is very important because it helps us to be better in our profession; like you
mentioned “it gives the user the power to access and interpret data.”
Raggousis,
After reading your post, I
have a strong idea of what Structured Query Language is and what are its most important
aspects. Thanks for breaking this down; it was very easy to read it. I did use Access
before and I think this software is very powerful. I also believe this system
has no barriers and it allows people (with businesses) to develop their
internal databases. It is impressive how much SQL can offer to this world. SQL
is very important because they offer to every single company to have more productivity
and organization; I believe this is what all companies want nowadays. I like when you mentioned “SQL is important
because without it, you lose productivity, efficiency, and organization;” you
are correct!! I enjoyed reading your post.
Selden,
I liked the way you
summarize databases in construction. It seems that databases are very useful to
during and after construction. I believe that scheduling is the most important part
of a new project. Not having a good visualization of what is going on with the
project, contracts, delays, and errors, can affect the engineering firm in charged
on the project. This is why I believe that putting all together can help during
and after construction. I like when you mentioned that “The construction industry
is one that has extensive amounts of information, which makes the creation and
use of the database somewhat simpler.” It is obviously that databases are more
than numbers, they provide a lot of efficiency and productivity; his is the main
reason industries use them.
I think you did a good job explaining the relational databases. You made it easy to understand the structure and how they relate. I would like to hear a little more about how these are actually used, as I am new to all of these programs.
ReplyDeleteYour post was very informational. Prior to this I had no knowledge on the Relational Databases. The images were especially informative. SQL sounds very interesting and I would particularly like to understand them better.
ReplyDeleteAfter completing my post, I was very curious about SQL. Your break down of the four different languages was very helpful. I also really enjoyed your images, they helped in understanding the process.
ReplyDelete