Database & SQL (Week 9)

This week, the lecture class was about the database and SQL. I remembered in my first semester, I took the database subject. Therefore, I have some knowledge about database and below is my summary for database and SQL.

According to Mannino (1990, cited in Databases Lecture Slides 2009), database is a collection of persistent data that can be shared and interrelated. There are some characteristics of data in databases:

• Persistent (stored).
• Inter-related.
• Shared.

Moreover, Database Management System (DBMS) is a software system that enables users to define, create, maintain, and control access to the database (Connolly & Begg cited in Databases Lecture Slides 2009). Nowadays, there are many DBMS software in the marketplace (Databases Lecture slides 2009):

1. Enterprise DBMS

• Oracle : dominates in Unix, strong in Windows.
• SQL Server : strong in Windows.
• DB2 : strong in mainframe environment.
• Significant open source DBMSs : MySQL, Firebird, PostgreSQL.

2. Desktop DBMS

• Access : dominates.
• FoxPro, Paradox, Approach, FileMaker Pro

There are also some features of commercial DBMSs (Databases Lecture Slides 2009):

• Database definition.
• Non-procedural data access.
• Application development.
• Procedural language interface.
• Transaction processing.

Furthermore, a relational database is a collection of tables (Databases Lecture Slides 2009). There are some terms in database:

• Fields (columns).
• Data types: CHAR, VARCHAR, INT, SMALLINT, FLOAT, DATE/TIME, DECIMAL, BOOLEAN.
• Records (rows).
• Tables.
• Keys.
• Superkey : column(s) with unique values.
• Candidate key : minimal superkey.
• Primary key : a designated candidate key and cannot contain null values
• Foreign key : column(s) whose values must match the values in a candidate key of another table.
• Relationships.
• Relational database.
• The ordering of rows has no significance.
• The ordering of columns has no significance
• Row must be unique
• Cell values must be atomic
• Relational Database Management System.

Structure Query Language (SQL) is a database computer language designed for managing data in relational database management system (RDBMS) (Wikimedia Foundation 2010). There are four basic operations in SQL (Weakley 2010):

• Adding (inserting) data.
• Finding (selecting) data.
• Updating (modifying) data.
• Deleting data.

References

• Weakley, A. 2010, Databases & Structured Query Language, University of Technology Sydney, Sydney, viewed 4 May 2010, (https://online.uts.edu.au/courses/1/95564/content/_353009_1/dbmsAndSQL.pdf?bsession=38305700&bsession_str=session_id=38305700,user_id_pk1=251384,user_id_sos_id_pk2=1,one_time_token=).
• School of Software, Faculty of Engineering and Information Technology, UTS. 2009, 'Databases Lecture Slides', UTS, Sydney.
• Wikimedia Foundation 2010, SQL, Wikimedia Foundation, viewed 4 May 2010, (http://en.wikipedia.org/wiki/SQL).