1. Designing a Database Unleashing the Power of Relational Database Design

2. Understanding Databases There are three basic kinds of databases called (1) flat file, (2) relational, and (3) object-oriented. A flat file database keeps all of the records in a single file, in which the data elements are separated by a break character such as a comma or a tab. The terms comma-delimited or tab- delimited refer to data stored in this manner.

3. Comma Delimited Data

4. What Is a Data Table? Flat file databases typically contain just one data table, which is a database structure that organizes the data into rows and columns. Each row contains one record, and the columns contain the data fields that the record comprises.

5. Visualizing a Data Table

6. What Is a Relational Database? A relational database is a data structure that comprises multiple tables containing primary key columns through which the records in one table can relate (i.e., key) to the data in another table. A data table’s primary key is a column in which every entry is unique. A foreign key is a data field that relates the record to the table in which that same column occurs as a primary key.

7. Visualizing Relational Data

8. What Is an Object-Oriented Database? The third and final kind of database is called object-oriented, in which programmers writing code in object- oriented languages can create complex data structures in which one data type can build upon, or inherit, properties from another. In this course, we deal with relational databases.

9. Database Design Principles Each table should have a column containing a unique row ID number to serve as the table’s primary key. A table should store data for a single type of entity. A table should avoid columns that are allowed to contain null values. If you must have empty values, use an empty string.

10. Database Design Principles (continued) A table should not have repeating values. A field should have the same meaning in each row of a table. Multiple instances of an entity should not be represented as multiple columns.

11. Three-Tier Web Application Model