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MySQL Tutorial 1 –
How to Use MySQL
CSCI 2140
TA: Jiye Li [email protected]
May 26, 2005
http://flame.cs.dal.ca/~jiye/CSCI2140/
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Agenda
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Getting familiar with
our network system
Introducing MySQL
SQL basics
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create, add, select, modify, delete
Exercises (see handout)
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How to get a UNIX account
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Sun workstation or ssh program (putty)
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Log into torch.cs.dal.ca
Username: discover
Passwd: query
Enter your student number
Ask Help Desk
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How to get a Windows account
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Username: the same as torch account
Password: student ID number. Don’t
forget ‘B’ is capitalized.
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What is MySQL?
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MySQL is a database management
system (DBMS) for relational databases
Online Manual
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http://dev.mysql.com/doc/
MySQL is installed on torch
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Each user ID stands for a database
Create tables under this database
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How to Login to MySQL
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Go on torch.cs.dal.ca
Run mysql to login
Lower case
Student ID
torch: ~$ mysql -p
Enter password:
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 123943 to server version: 4.0.12
Type 'help;' or '\h' for help. Type '\c' to clear the buffer.
mysql>
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How to Logout

Use the command exit or quit
torch: ~$ mysql -p
Enter password:
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 123975 to server version: 4.0.12
Type 'help;' or '\h' for help. Type '\c' to clear the buffer.
mysql> exit
Bye
torch: ~$
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Use your database

After login MySQL, use your own
database before creating tables
torch: ~$ mysql -p
Enter password:
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 125213 to server version: 4.0.12
Type 'help;' or '\h' for help. Type '\c' to clear the buffer.
mysql> use jiye;
Database changed
mysql>
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Your user ID
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SQL Basics

Suppose we would like to create a few
tables, such as employee table,
employer table and payment table,
representing a database about
employee information.
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How to write commands in MySQL
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How to create a table
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Primary Keys and Foreign Keys
How
How
How
How
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to
to
to
to
add records
select records
modify records
delete records
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How to create tables
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Use create
create table <table_name>
(column_name data_type [not null] … ,
column_name data_type [not null],
primary key (column_name));
To show the structure of the table
describe <table_name>;
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Example
mysql> create table employee (
empno smallint(4) not null auto_increment,
name char (8) not null,
job char (4) ,
salary int (8) not null,
deptno int (4) not null,
primary key (empno)
);
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Primary Key
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Primary Key is a column or set of
columns
Uniquely identifies the rest of the data
in any given row.
For Example: in the employee table,
employee number is the primary key.
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Foreign Key
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A foreign key is a column in a table
This column is a primary key of another
table
Any data in a foreign key column must
have corresponding data in the other
table
http://dev.mysql.com/doc/mysql/en/innodb-foreign-keyconstraints.html
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Foreign Key
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The goal of using foreign keys is that,
tables can be related without repeating
data
Note that foreign keys in SQL are used
to check and enforce referential
integrity, not to join tables. If you want
to get results from multiple tables from
a SELECT statement, you do this by
performing a join between them:
SELECT * FROM t1, t2 WHERE t1.id = t2.id;
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Example – Create table with
employee2
foreign keys
create table employee2 (
empno smallint(4) not null,
salary float,
primary key (empno)
) type = innodb;
create table employer (
id smallint(4),
employee_no smallint(4),
index employ_ind (employee_no),
foreign key(employee_no)
references employee2(empno)
on delete cascade) type=innodb;
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empno
(PK)
salary
100
200.85
200
129.54
300
98.17
employer
id
employee_no(FK)
51
100
52
100
53
200
54
300
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The Syntax of a Foreign Key
Constraint Definition
[CONSTRAINT [symbol]] FOREIGN KEY
(index_col_name, ...) REFERENCES table_name
(index_col_name, ...) [ON DELETE {CASCADE | SET
NULL | NO ACTION | RESTRICT}] [ON UPDATE
{CASCADE | SET NULL | NO ACTION | RESTRICT}]
 Both tables have to be InnoDB type
 InnoDB provides MySQL with a transaction-safe
storage engine with commit, rollback, and crash
recovery capabilities.
http://dev.mysql.com/doc/mysql/en/innodboverview.html
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The Syntax of a Foreign Key
Constraint Definition
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InnoDB rejects any INSERT or UPDATE operation that
attempts to create a foreign key value in a child table
without a matching candidate key value in the parent table.
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CASCADE: Delete or update the row from the parent table and automatically delete
or update the matching rows in the child table.
SET NULL: Delete or update the row from the parent table and set the foreign key
column(s) in the child table to NULL. This is only valid if the foreign key columns do
not have the NOT NULL qualifier specified.
NO ACTION: NO ACTION means no action in the sense that an attempt to delete or
update a primary key value will not be allowed to proceed if there is a related
foreign key value in the referenced table.
RESTRICT: Rejects the delete or update operation for the parent table. NO ACTION
and RESTRICT are the same as omitting the ON DELETE or ON UPDATE clause.
(Some database systems have deferred checks, and NO ACTION is a deferred check.
In MySQL, foreign key constraints are checked immediately, so NO ACTION and
RESTRICT are the same.)
SET DEFAULT: This action is recognized by the parser, but InnoDB rejects table
definitions containing ON DELETE SET DEFAULT or ON UPDATE SET DEFAULT
clauses.
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MySQL Table Types
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If we want to use Foreign Key
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Otherwise
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InnoDB tables
Default table type, MyISAM
In SQL queries you can freely mix
InnoDB type tables with other table
types of MySQL, even within the same
query.
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How to add records

Use insert
insert into <table_name> values
(column_value, …, column_value);
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Example
insert into employee values (1000,'Wilson','Clrk',1700,10);
insert into employee values (1001,'Smith','Slsm',2500,40);
insert into employee values (1003,'Reed','Anlt',3500,30);
insert into employee values (1005,'Watson','Mngr',4500,30);
insert into employee values (1009,'Allen','Mngr',3800,40);
insert into employee values (1010,'Turner','Clrk',1800,50);
insert into employee values (2000,'Chen','Mngr',2900,10);
insert into employee values (2100,'Ramirez','Mngr',3650,50);
insert into employee values (2130,'McDonnel','Clrk',1625,60);
insert into employee values (2140,'Simpson','Drvr',825,60);
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Example On Slide 17
insert into employee2 values (100, 200.85);
insert into employee2 values (200, 129.54);
insert into employee2 values (300, 98.17);
insert
insert
insert
insert
into
into
into
into
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employer
employer
employer
employer
values
values
values
values
(51,
(52,
(53,
(54,
100);
100);
200);
300);
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How to Select Records
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select * from <table_name>;
select * from <table_name> where
<column_name> = <qualifier>;
select * from <table_name> where
<column_name> = <qualifier> order by
<column_name>;
select <column_name, …> from
<table_name>;
select <distinct column_name, …> from
<table_name>
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Example
select * from employee;
select * from employee where empno = 1000;
select * from employee where job = 'Clrk' order by salary;
select name, empno from employee;
select job from employee;
select distinct job from employee;
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Example On Slide 17
select empno from employee2;
select empno from employee2
where salary >=50 and salary < 150;
select * from employee2, employer;
select id, empno from employer m, employee2 n
where m.employee_no = n.empno;
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How to Modify Records

Use update to modify attribute values of
(some) tuples in a table
update <table_name> set <column i >
= <expression i>, …, <column j> =
<expression j> [where <condition>];
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Example
update employee set job = ‘Drvr’, deptno = 20 , salary =
salary + 1000 where name = 'Reed’;
update employee set salary = salary * 1.15 where
deptno in (10, 40);
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How to Delete Records

Use delete
delete from <table_name> [where
<condition>];
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Example
delete from employee where
salary < 2000;
delete from employee;
Note: this command will delete all the
records in the “employee” table.
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Tip1: How to Load Command
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Execute a SQL script file.
Take a file name as an argument.
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Save SQL commands into a file <name>
Execute the commands:
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mysql> source <name>;
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Example
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In file “temp.sql”
select * from employee;
select name from employee where
salary < 3000;
mysql> source temp.sql;
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Tip2: How to Save Results
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Save results
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tee <file>
Set outfile. Append everything into given
outfile <file>. All the information displayed
on screen is stored in <file>.
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Example
mysql>tee result;
mysql> select * from employee;
mysql> notee;
mysql> exit
torch: ~$ cat result
mysql> select * from employee;
EMPNO NAME
JOB
SALARY
DEPTNO
---------- -------- ---- ---------- ---------1000 Wilson Clrk
1720
10
1001 Smith Slsm
2500
40
…………
10 rows selected.
mysql> notee;
torch: ~$
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Appendix: MySQL Data Types
Type
Size
Description
tinyint[Length]
1 byte
Range of –128 to
127
float
4 bytes
A small number with
a floating decimal
point
Date
3 bytes
In the format of
YYYY-MM-DD
Time
3 bytes
In the format of
HH:MM:SS
varchar[Length]
String length + 1
byte
A fixed-length field
from 0 to 255
characters long
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Appendix: MySQL under Unix
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A few commands
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use username;
show tables;
show columns from employee;
help;
exit;
SQL commands (select, insert, delete,…)
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Appendix: MySQL Control Center
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Graphical user interface (GUI) to the
MySQL database server
Supports interactive use, including
syntax highlighting and tab completion
Download from
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http://dev.mysql.com/downloads/other/my
sqlcc.html
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Appendix: MySQL Control Center
Student ID
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