Introduction databases and MYSQL

size
ease of updating
accuracy
security
redundancy
importance

Database Management Systems(DBMS)
Oracle
SQL Server
MySQL
PostgreSQL
MongoDB
…

DBMS
Software
database database
Other DBMS

FirstName LastName HireDate Grade Salary City
table
columns
rows

FirstName
(text)
LastName
(text)
HireDate
(Date)
Grade
(numeric)
Salary
(currency)
City
(text)
table
columns
rows

FirstName
(text)
LastName
(text)
HireDate
(Date)
Grade
(numeric)
Salary
(currency)
City
(text)
James Black 03/10/2014 7 15000 HYD
table
columns
rows

FirstName
(text)
LastName
(text)
HireDate
(Date)
Grade
(numeric)
Salary
(currency)
City
(text)
FirstName LastName 03/10/2013 8 15000 CA
James Black 03/10/2014 7 15000 HYD
table
columns
rows

WHAT IS A DATABASE?
•A database is a bunch of information
–It is a structured collection of information
–It contains basic objects, called records or entries
–The records contain fields, which contain defined types of
data, somehow related to that record.
–A university database would contain for example all kinds
of students as records, and students properties (ID,name,
etc) as fields.

WHAT IS A DATABASE?
•A database is searchable
–It contains an index (table of content, catalog)
•It is updated regularly
–New data goes in
•Obsolete, old data goes out
–It is cross referenced To other databases

WHY DATABASES?
•The main purpose of databases is not only to collect and
organize data, but to allow advanced data retrieval and
analysis
•A database query is a method to retrieve information from the
database
•The organization of records into fields allows us to use
queries on fields.

DATABASES ON THE INTERNET
USER
DATABASE
SERVER
WEBSERVERS

ROAD MAP
•Introduction to MySQL
•Connecting and Disconnecting
•Entering Basic Queries
•Creating and Using a Database

MySQL
•MySQL is a very popular, open source database.
•Officially pronounced “my Ess Que Ell” (not my sequel).
•Handles very large databases; very fast performance.
•Why are we using MySQL?
–Free (much cheaper than Oracle!)
–Each student can install MySQL locally.
–Easy to use Shell for creating tables, querying tables, etc.
–Easy to use with PHP

CONNECTING TO MYSQL
•MySQL provides an interactive shell for creating tables,
inserting data, etc.
•On Windows, just go to c:mysqlbin, and type:
•Mysql –u root -p
•Or, click on the Windows icon

SAMPLE SESSION
 For example:
Enter password: *****
Welcome to the MySQL monitor. Commands end with ; or g.
Your MySQL connection id is 241 to server version: 3.23.49
Type 'help;' or 'h' for help. Type 'c' to clear the buffer.
mysql>
 To exit the MySQL Shell, just type QUIT or EXIT:
mysql> QUIT
mysql> exit

BASIC QUERIES
 Once logged in, you can try some simple queries.
 For example:
mysql> SELECT VERSION(), CURRENT_DATE;
+-----------+--------------+
| VERSION() | CURRENT_DATE |
+-----------+--------------+
| 3.23.49 | 2002-05-26 |
+-----------+--------------+
1 row in set (0.00 sec)
 Note that most MySQL commands end with a semicolon (;)
 MySQL returns the total number of rows found, and the total time to
execute the query.

BASIC QUERIES
 Keywords may be entered in any lettercase.
 The following queries are equivalent:
mysql> SELECT VERSION(), CURRENT_DATE;
mysql> select version(), current_date;
mysql> SeLeCt vErSiOn(), current_DATE;

BASIC QUERIES
 Here's another query. It demonstrates that you
can use mysql as a simple calculator:
mysql> SELECT SIN(PI()/4), (4+1)*5;
+-------------+---------+
| SIN(PI()/4) | (4+1)*5 |
+-------------+---------+
| 0.707107 | 25 |
+-------------+---------+

BASIC QUERIES
 You can also enter multiple statements on a
single line. Just end each one with a semicolon:
mysql> SELECT VERSION(); SELECT NOW();
+--------------+
| VERSION() |
+--------------+
| 3.22.20a-log |
+--------------+
+---------------------+
| NOW() |
+---------------------+
| 2004 00:15:33 |
+---------------------+

MULTI-LINE COMMANDS
 mysql determines where your statement ends by
looking for the terminating semicolon, not by
looking for the end of the input line.
 Here's a simple multiple-line statement:
mysql> SELECT
-> USER()
-> ,
-> CURRENT_DATE;
+--------------------+--------------+
| USER() | CURRENT_DATE |
+--------------------+--------------+
| joesmith@localhost | 1999-03-18 |
+--------------------+--------------+

CANCELING A COMMAND
 If you decide you don't want to execute a
command that you are in the process of entering,
cancel it by typing c
mysql> SELECT
-> USER()
-> c
mysql>

USING A DATABASE
 To get started on your own database, first check
which databases currently exist.
 Use the SHOW statement to find out which
databases currently exist on the server:
mysql> show databases;
+----------+
| Database |
+----------+
| mysql |
| test |
+----------+
2 rows in set (0.01 sec)

USING A DATABASE
 To create a new database, issue the “create
database” command:
 mysql> create database webdb;
 To the select a database, issue the “use” command:
 mysql> use webdb;

CREATING A TABLE
 Let’s create a table for storing pets.
 Table: pets
 name: VARCHAR(20)
 owner: VARCHAR(20)
 species: VARCHAR(20)
 gender: CHAR(1)
 birth: DATE
 date: DATE

CREATING A TABLE
 To create a table, use the CREATE TABLE
command:
mysql> CREATE TABLE pet (
-> name VARCHAR(20),
-> owner VARCHAR(20),
-> species VARCHAR(20),
-> gender CHAR(1),
-> birth DATE, death DATE);
Query OK, 0 rows affected (0.04 sec)

SHOWING TABLES
 To verify that the table has been created:
mysql> show tables;
+------------------+
| Tables_in_test |
+------------------+
| pet |
+------------------+
1 row in set (0.01 sec)

DELETING A TABLE
 To delete an entire table, use the DROP
TABLE command:
mysql> drop table pet;
Query OK, 0 rows affected (0.02 sec)

Introduction databases and MYSQL

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