SQL and Relational DBMS

A Database Management System (DBMS) is a set of logically related programs that enables storing, modifying, and extracting information from one location efficiently. The users can access the stored data by using programming interface to modify or retrieve the information, which can be presented in a variety of formats. Some examples of databases are airline reservation systems, banking systems, computerized parts inventory systems. As Jeanine mentioned in her blog, there are two major types of databases, relational and object-oriented databases.

The relational DBMS was proposed for the first time in 1970s by Edgar Codd. It stores all the data as logically structured relations or two-dimensional tables, where each table corresponds to an entity and each row corresponds to an instance of the entity. The different table of records can be connected by common key parameters and exchange information. Construction companies use relational database management systems for cost estimation and cost control; System Analysis and Design (SAD) is used to develop an integrated model which enables the transfer of the cost estimation data to the cost control processes.

System Query Language (SQL) is a self-contained data language that most databases organized according to the relational structure use; it solely exist to support the data language. It is a tool for managing, organizing and retrieving stored information from a database. For instance, when the user needs to retrieve data from a database, they use SQL to request it. Then, the DBMS processes the SQL request, retrieves the data and returns it back to the user. In the 21st century NoSQL was created, for non-relational databases, where tables do not require to be in fixed table schemas or the data stored doesn’t have to be normalized.

Figure 1 shows some components of the SQL and how it links everything together. 

Figure 1. Components of a typical DBMS

SQL is a powerful and useful tool that links people, computer programs and systems to the data stored in a relational database; thus it is very important to have a well written standardized language that allows everyone to access and manipulate databases. However, as Tom said, SQL is no a complete language - a lot of times it is embedded in another language. It has multiple functions that are necessary for understanding and using databases and over the years SQL has expanded to support the new technology, hardware, operating systems and languages. 

Sources:

Salman Azhar, Syed M. Ahmed and Amaury A. Caballero. “Development of an Integrated Cost Estimation and Cost Control System for Construction Projects,” http://fire.nist.gov/bfrlpubs/build02/PDF/b02054.pdf

Ramon A. Mata-Toled. "Database management system." in AccessScience, ©McGraw-Hill Education, LLC. 2012. http://www.accessscience.com.ezproxy2.library.drexel.edu

James R. Groff and Paul N. Weinberg. “Introduction to SQL.” 2004. http://www.devarticles.com/c/a/SQL/Introduction-to-SQL/2/