Using Relational Databases and SQL Steven Emory Department of Computer Science California State University, Los Angeles Lecture 1: Introduction to Relational Databases and MySQL

Database Origin Database comes from the open compound word “Data Base” Data Base was a military term (circa 1964) Data Base implies data that is both persistent and shared (think Air Force Base) The military funded much of the research into the early electronic computers of the 40’s and 50’s because of World War II and the Korean War

What is a Database? A structured collection of persistent data that is typically meant to be shared Used to model organizational activities Structure is defined through a database model No database model, no database! Examples: Airlines, Banks, Stores and Universities

Database Models The Two Levels of a Database Model Physical Level (how data is stored)‏ The things we don’t care about Logical Level (how data is generalized)‏ The things we do care about The Basic Models Hierarchical Model‏ (IBM’s IMS) Network Model (CODASYL)‏ Relational Model (ALPHA, SEQUEL)‏

Physical/Logical Separation Previous to the relational model, one had to write a program that traversed pointers at the physical level to extract data from a database (think like programming in assembly language) By abstracting the physical level and writing a program at the logical level instead (think like programming in Java), extracting data from a database became easier First proposed by Dr. Edgar Frank Codd.

Dr. Edgar F(rank) Codd MA Mathematics, MA Chemistry MS and PhD in Communication Sciences ACM Turing Award (1981)

Relational Model Proposed by Edgar F. Codd (circa 1969)‏ Database is a collection of tables (relations) Relational comes from ‘Relational Algebra/Calculus’ and not from ‘Relationships’ Relational model is very mathematical Dominant database model Thanks to Larry Ellison, founder of Oracle, who was first to aggressively market a commercial relational database product (Ellison is currently the 4 th richest person in the world)

Tables‏ Artists = Table (Relation)‏ ArtistID, City, Region,... = Columns (Attributes)‏ Each row is called a Record (Tuple)‏

Data Types‏ Determines storage requirements Common attribute types String Numeric (float, double, real)‏ Date and Time Blobs and Clobs (images and other binary data)‏

Database Schemas The definition of the database, where you define The name of the database Tables Column names, types, and constraints Relationships between tables Stored functions and procedures Schemas are typically represented by a schema diagram

Database Schemas

Database Management Systems (DBMS)‏ Software (programs) to manage databases Creation/Deletion Maintenance (inserting, updating‏, and deleting records) Security (encryption, user access control)‏ Common DBMSs MySQL, PostreSQL (open source)‏ Oracle, DB2, MS SQL Server (commercial)‏

Database Management Systems (DBMS) You can have multiple databases, each with a single schema A separate database for each application Toystore (First database) Bookstore (Second database) Furniture Store (Third database) Etc. You can also have a single database, with multiple schemas

DBMS Diagram

Query Languages Query Language = A language used to extract data from a database Domain-Specific Language Only for databases History Codd, Alpha (1971)‏ Chamberlin and Boyce, SEQUEL (1974)‏ Eventually renamed to SQL

QL Examples Alpha (Codd) SEQUEL (Chamberlin, Boyce)‏

SQL Stands for Structured Query Language A non-procedural, domain-specific language (not like C or C++)‏ An open ANSI standard Supported by most major DBMS Some variations in implementations Used by programmers, managers, and database administrators

SQL Functions View information from relational databases Single and multiple table selections Calculation and analysis Manipulate information in relational databases Insert and delete records Update records Create relational databases Create databases, tables, constraints,...

Other Interesting Facts Question: Why is a database always represented by an aluminum can or some type of cylinder?

Other Interesting Facts Answer: Because that’s what disk storage looked like back in the old days!

Other Interesting Facts Since IBM already had a database product called IMS, which was currently being used in the Apollo space program (1969 – 1972), Dr. Codd was asked by IBM not to disparage IMS nor promote his model over IMS since it might hurt sales of IMS. Many people to this day believe that hindered IBM and Dr. Codd from making all the money that Larry Ellison of Oracle has made.

Downloading MySQL Go to CS122 Wiki page and under the Required Software section, click on the links to MySQLMySQL (client and server program) MySQL GUI Tools MySQL GUI Tools (alternative client program) MySQL Workbench MySQL Workbench (schema utility) Download the versions for Windows, without the installer Extract all three to a flash drive (preferably)

Important Notes!!! You can put MySQL directly onto these computers, but be aware that other students may delete your stuff (by accident or otherwise) Do not leave homework, labs, or programs on our computers as other students may find and mishandle your stuff Always back up your work onto a personal flash drive before you leave Don’t forget your flash drives