Blog Post 5 - Relational Database Theory

A relational database is a database model that stores data in tables. The rows in a relational database table are the records, and the columns are the fields, which together form the relation [1]. The table can be viewed as a matrix in which all records share the same fields [1]. Structured Query Language (SQL) is the "standard way to access data from a relational database" [1]. Relational databases are easy to create, access, and add on to; making them very useful in the engineering world [2]. 

Databases can be in three different relationship types: one to one, one to many, many to many. If we think of this like through family dynamics it becomes easier to understand. A one to one relationship is like you and your spouse; you are only paired with each other. A one to many relationship is like you and your children; they only have one mother, but you have many children. A many to many relationship is like you and your siblings; you have many siblings and your siblings have many siblings [4].

Figure one below shows an example of where and how a relational database can be used. The relational data base is used to store employe information. The employee number, name, and department for each employee are the records. The employee number, name, and department attributes are the fields. If you had a few thousand employees, having their employee number could help you find all other attributes about him or her.

Figure 1

Relational databases are more advantageous because of the following [3]:

• Avoids data duplication
• Avoids inconsistent records
• Easier to change data
• Easier to change data format
• Data can be added and removed easily
• Easier to maintain security

Relational databases have two main issues [5]:

• Incomplete information
• Updates loosing information

Works Cited:

1. "Relational Database." Relational Database Definition. Sharpened Productions, 2017. Web. 14 Feb. 2017. <https://techterms.com/definition/relational_database>.
2. Rouse, Margaret. "What Is Relational Database?" SearchSQLServer. TechTarget, Apr. 2006. Web. 14 Feb. 2017. <http://searchsqlserver.techtarget.com/definition/relational-database>.
3. "Relational Database Advantage." Teach-ICT. Teach-ICT, 2017. Web. 14 Feb. 2017. <http://www.teach-ict.com/as_as_computing/ocr/H447/F453/3_3_9/database_design/miniweb/pg8.htm>.
4. Harkins, Susan. "Relational Databases: Defining Relationships between Database Tables." Tech Republic. Tech Republic, 30 Apr. 2003. Web. 14 Feb. 2017. <http://www.techrepublic.com/article/relational-databases-defining-relationships-between-database-tables/>.
5. Wambler, Scott. "Relational Databases 101: Looking at the Whole Picture." Relational Databases 101: Looking at the Whole Picture. Agile Data, 2013. Web. 14 Feb. 2017. <http://www.agiledata.org/essays/relationalDatabases.html>.

Responses:

1. Prahlad Singh - I really enjoyed reading your post because you gave so many examples of reasons to have databases in our industry. I agree with you that databases cut down on cost and improve efficiency in our field. I like that you incorporated the positives to the construction management field as well. https://ae-410-510-ay16-17.blogspot.com/2017/02/b5-singh-prahlad.html
2. Ronald Herazo - After 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. https://ae-410-510-ay16-17.blogspot.com/2017/02/assignment-b5-group-ronald-herazo.html
3. Elga Qori - Your post really helped me understand SQL and its importance. The use of SQL is very important in order for the user to adjust the data and learn from it. The image you provided of the operators table really helped me understand the many different ways SQL can adjust the data. https://ae-410-510-ay16-17.blogspot.com/2017/02/b5-sql-egla-qori.html