1. Database Organization and Design
Chapter 1
Adapted from slides by Raghu Ramakrishnan,

2. What is a DBMS?
A database is a (very) large, integrated collection of data
A database is based upon a data representation (data model) of a real-world enterprise
Objects (or Entities, e.g., students, courses)
Relationships (e.g., Charlie Brown is in CS3610)
A Database Management System (DBMS) is a software package designed to store and manage databases. E.g., UNIDATA, mysql, or Access

3. File Storage vs. a DBMS
A DBMS can “stage” data (for large datasets) between main memory and secondary sources (disk, CD, tape)
A DBMS provides efficient (indexed) access
A DBMS provides a built-in query language to facilitate data retrieval
Permits free form queries
Standard language provides standard communication for programs using embedded queries
A DBMS protects data from inconsistency by
Enforcing referential integrity during data modification
Enforcing data format constraints
Providing controlled concurrent access
A DBMS provides crash recovery
A DBMS provide multi-level security and access control
A DBMS allows for uniform administration of the data

4. Data Models
A data model is the manner in which you describe some data.
The Entity Relationship Diagram (ERD) represents a conceptual data model for describing objects and their relationships. The ERD is the most common of the conceptual data models. It has several variants.
Main features of an ERD is entities, attributes, and relationships.
The relational data model is a conceptual data model for implementing a database. The relational model is easily the most widely used model today.
Main concept the relation: a table of records and fields
Every relation has a defining schema
A schema is the description of a particular collection of data in a given data model.

5. Levels of Abstraction View 1 View 2 View 3 Conceptual Schema
Physical Schema

6. Example: University Database
External View:
View1: course_info ( course_name, enrollment )
View2: teacher_info ( course_name, teacher )
Conceptual Schema
Students(sid, name, age, gpa)
Courses (cid, name, credits)
Teachers (tid, name, rank)
Enrolled (sid, cid, grade)
Teaches (tid, cid)
Physical Schema
Store relations as tables
Index tables by id fields

7. Road Ahead Modeling Data with Entity Relationship Diagrams
Using the Relational Model (i.e., Schema Descriptions) to Model Data
Relational Algebra: A concise language for describing data operations
Structured Query Language (SQL): A standard language for manipulation of data by computers
Database Apps: Learning how to access databases from programs
Database File Organization, Storage, and Indexing

8. Road Ahead (Continued)
Hash Indexes
Query Evaluation: Getting the resultant data for the (somewhat) least cost
Transaction Management: Keeping multiple users from interfering with each other
Schema Design and Normal Forms: Reducing redundancy in the database
Physical Database Design: Tuning your database for performance