# Database Management Systems

## Course Description

Introduction to database management systems, including data modeling, query languages and processing, database design, data integrity and security. Issues related to distributed database systems, object-oriented database systems, and legacy database systems are also discussed.

## Purpose, Goals & Objectives

Introduction to database management systems, including data modeling, query languages and processing, database design, data integrity and security. Issues related to distributed database systems, object-oriented database systems, and legacy database systems are also discussed. At the conclusion of this course a student will:

1. Understand the difference between the file-oriented method of building applications and the database method.
2. Learn and practice data modeling using the E-R model.
3. Learn and practice designing normalized databases using the E-R.
4. Learn the fundamentals of the relational data model and understand its role in database implementation.
5. Learn and practice SQL and Relational Algebra.
6. Design and implement a relational database and application in C# using SQL server.
7. Understand the implications and problems of enterprise database systems and study solutions to some of the problems.
8. Understand the role of the "people" involved in a database system.
9. Understand the need for data warehousing and mining applications.
10. Understand the uses of spatial temporal and constraint databases.

# Resources

### Database Management Systems Child Pages

This class is about Database Management Systems. As such we talk about creating, managing and programming SQL databases. When time permits, we also cover spatial/spatial temporal data and database systems. This site contains content developed by Dr. Anderson for his classes.

## Accessing the Database using Visual Studio Code

First off, we will be using Visual studio Code for all our database needs! You will not need to install any other tool, AND this tool runs on everything!

If you haven't done so, install the mssql extension.

1. Click the extensions icon on the left tool bar.
2. Search for and install mssql extension.

To use Visual Studio code mssql plugin

1. Press CTRL+N. Visual Studio Code opens a new 'Plain Text' file by default.
2. Press CTRL+K,M and change the language mode to SQL.
3. Alternatively, open an existing file with .sql file extension. The language mode is automatically SQL for files that have the .sql extension.
4. press CTRL+SHIFT+P (or F1) to open the Command Palette.
5. Type sqlcon and press ENTER. (Select the MS SQL: Connect command.)
6. Select Create Connection Profile. This creates a connection profile for your SQL Server instance.
7. Follow the prompts to specify the connection properties for the new connection profile. After specifying each value, press ENTER to continue.

   1 --Press: Ctrl+Shift+E to execute a query
2 --To execute a specific query, hightlight the query before you execute it.
3
4 -- To see a list of databases try:
5 select *
6 from sys.databases;
7
8 -- To select a database to use try:
9 Use UniversitySmall;
10
11 -- To Show the tables in a database try:
12 SELECT *
13 FROM information_schema.tables;


## Database diagrams

• We are now using Vertebelo for database diagrams.

## Programming & Design Resources

Learning to program something more complex than a one off programming assignments for students can be difficult. Where do the experts learn to program large database applications and what tools and methods do they use? This section is not an answer, but a suggestion on where to look for those answers. Someday, I hope to have a class that explores this in depth.

And many more to follow I'm sure.

## Project Ideas

See: Project Ideas

## Chapter Notes and Hints

These notes and hints serve to review you for exams and to help you with your homework. Occasionally you will find information here that is not in the book. You should READ THIS BEFORE YOU DO YOUR HOMEWORK!

### Chapter 3 and 4 Hints

If you are having problems joining tables in the FROM and WHERE clauses, you are in the majority. There are two hints that I will give you to help you obtain the right perspective on joining tables:

Rule 1: Just because two attributes have the same name doesn't mean that you should join them on these attributes. STOP, THINK about the semantics (the meaning) of the attribute. Do they both refer to the same thing? If the answer is yes, then you should join on them. Using NATURAL JOIN will match strings, not semantics, so be careful. Also NATURAL JOIN "works" but not on most systems and even on Oracle it is not encouraged... so DON'T USE IT ON YOUR HOMEWORK. If you do I'll run it on Oracle. If it doesn't work, you will be docked points accordingly.

Rule 2: When you are looking at the attributes and relations, something is a foreign key only if it is the primary key in a different relation. Even if the foreign key is part (but not all) of the key in the relation it is in, it is a foreign key.

Rule 3: The book doesn't always give you all the attributes that make up the primary key. Look carefully at the values and make sure when you create tables in Chapter 4 that the attributes you select to be the primary key are sufficient to uniquely identify a each row.

### Chapter 6.1: Relational Algebra

Rule 1: You don't need to qualify the results of a natural join. The results of a natural join ALWAYS only have one copy of overlapping attributes.

Rule 2: Predicates, attribute lists and functions in $$\sigma, \Pi, \mathcal{G}$$ are always subscript.

Rule 3: Relations, whether expressions or names, NEVER appear as a superscript or subscript.

Rule 4: Input relations, whether expressions or name, always have parenthesis around them. E.g.

$$\Large~_{sect\_id,course\_id,year,semester}\mathcal{G}_{count(ID)}(student \bowtie takes)$$\$

### Chapter 7

Answers provided by the book to 7.2 seem a bit rough to me. You will find an image that expands on the book's answer here: Ch7.16 Annotated Drawings.pdf

### Chapter 8

#### Normal Forms

The following definition of a relation is adapted from Database Processing by Kronke. A relation has the following characteristics

• Rows contain data about an entity
• Columns contain data about attributes the entity
• All entities entries in a column are the same kind
• Each column has a unique name
• Cells of the table hold a single (atomic) value
• The order of the columns is unimportant
• The order of the rows is unimportant
• Now two rows may be identical

The following definitions are found in "Database System Concepts" Sixth Edition by Silberschatz, Korth and Sudarshan

First Normal Form p. 328 A relation $$R$$ is in first normal form if the domains of all attributes of $$R$$ are atomic.

Second Normal Form p. 372 A relation $$R$$ is in second normal form if each attribute $$A$$ in $$R$$ meets one of the following criteria:

• It appears in a candidate key
• It is not partially dependent on a candidate key.

Partial Dependency p. 372 A functional dependency $$\alpha \rightarrow \beta$$ is called a partial dependency if there is a proper subset $$\gamma$$ of $$\alpha$$ such that $$\gamma \rightarrow \beta$$. We say that $$\beta$$ is partially dependent on $$\alpha$$. \end{definition}

Third Normal Form p. 336 A relation schema $$R$$ is in third normal form with respect to a set $$F$$ of functional dependencies if, for all functional dependencies in $$F^+$$ of the form $$\alpha \rightarrow \beta$$, where $$\alpha \subseteq R$$ and $$\beta \subseteq R$$, at least one of the following holds:

• $$\alpha \rightarrow \beta$$ is a trivial functional dependency (that is, $$\beta \subseteq \alpha$$).
• $$\alpha$$ is a superkey for schema $$R$$.
• Each attribute $$A$$ in $$\beta - \alpha$$ is contained in a candidate key for $$R$$.

Boyce Codd Normal Form (BCNF) p. 333 A relation schema $$R$$ is in BCNF with respect to a set $$F$$ of functional dependencies if, for all functional dependencies in $$F^+$$ of the form $$\alpha \rightarrow \beta$$, where $$\alpha \subseteq R$$ and $$\beta \subseteq R$$, at least one of the following holds:

• $$\alpha \rightarrow \beta$$ is a trivial functional dependency (that is, $$\beta \subseteq \alpha$$).
• $$\alpha$$ is a superkey for schema $$R$$.

Fourth Normal Form pp. 358-359 A relation schema $$r(R)$$ is in fourth normal form with respect to a set $$D$$ of functional and multivalued dependencies if, for all multivalued dependencies in $$D^+$$ of the form $$\alpha \rightarrow \rightarrow \beta$$, where $$\alpha \subseteq R$$ and $$\beta \subseteq R$$, at least one of the following holds:

• $$\alpha \rightarrow \rightarrow \beta$$ is a trivial multivalued dependency.
• $$\alpha$$ is a superkey for schema $$R$$.

### Chapter 20

Using this data: Aircraft Data.xlsx

Import the data into a database and try the following query.

Try the following query:

USE Aircraft

GO

SELECT [Eng.HP], [Description], AVG(Cruise) AS AvgCruise,
AVG(TopSpd) AS AvgTopSpeed,
AVG([Gross Wt.]) AS AvgWt,
ORDER BY AvgFuelFlow;