MySQL

CSC 411/511: DBMS Design

Dr. Nan Wang CSC411_L12_MySQL1

MySQL

CSC411_L12_MySQLDr. Nan Wang22

Agenda

• Introduction to MySQL• Get Connected• Basic MySQL Commands• MySQL Syntax• Data Retrieval


• MySQL is a database management system.• MySQL is a relational database management

system.• The MySQL Database Server is very fast, reliable,

and easy to use.• MySQL Server works in client/server or embedded

systems.• A large amount of contributed MySQL software is

available.• MySQL software is Open Source.

– Download MySQL reference manualhttp://dev.mysql.com/doc/

– Download MySQLhttp://dev.mysql.com/downloads/

Overview of MySQL


Download MySQL

• Http://dev.mysql.com/downloads/• GUI Tools:

– MySQL Administrator 1.2 Generally Available (GA)– MySQL Query Browser 1.2 Generally Available (GA)– MySQL Migration Toolkit 1.1 Generally Available (GA)

4


Get connected

• To connect to the server, use the MySQL user name when you invoke mysql and, most likely, a password. • If the server runs on a machine other than the one where you

log in, you will also need to specify a host name. shell> mysql -h host -u user -p Enter password: ******** Type 'help;' or '\h' for help. Type '\c' to clear the buffer. mysql> • Disconnect it by typing QUIT (or \q) at the mysql> prompt: mysql> QUIT


• There are numerous command line options, but the most essential options and syntax are

• mysql -u<username> -h<hostname> -p[password] [database_name]

• If you leave out the -u option MySQL assumes the current shell user.

• If you leave out the host mysql assumes localhost – i.e., the machine you're logged onto.

• If you give it the -p option but no password, mysql prompts you for it.

Connection


Create and Use Database

• Create a database

mysql> CREATE DATABASE CSC411;

• Your database needs to be created only once, but you must select it for use each time you begin a mysql session.

mysql> USE CSC411Database changed

– or shell> mysql -h host -u user -p CSC411Enter password: ********


Creating a Table

• Creating the database is the easy part, but at this point it's empty, as SHOW TABLES tells you:

mysql> SHOW TABLES; Empty set (0.00 sec)

• Use a CREATE TABLE statement to specify the layout of your table:

mysql> CREATE TABLE pet (name VARCHAR(20), owner VARCHAR(20), -> species VARCHAR(20), sex CHAR(1), birth DATE, death DATE);

• Once you have created a table, SHOW TABLES should produce some output: mysql> SHOW TABLES; +---------------------+ | Tables in menagerie | +---------------------+ | pet | +---------------------+


• To verify that your table was created the way you expected, use a DESCRIBE statement:

mysql> DESCRIBE pet;

Describe statement


• In the most general terms, there are three types: numeric, string, and date/time.

• The concept of the NULL value – A common source of confusion for newcomers to SQL, who often think

that NULL is the same thing as an empty string. This is not the case. – For example, the following statements are completely different:

• mysql> INSERT INTO my_table (phone) VALUES (NULL);

• mysql> INSERT INTO my_table (phone) VALUES ('');

MySQL Data Types


Loading Data into a Table

• After creating your table, you need to populate it. The LOAD DATA and INSERT statements are useful for this.

• To load the text file pet.txt into the pet table, use this command: mysql> LOAD DATA LOCAL INFILE '/path/pet.txt' INTO TABLE pet;

• Note that if you created the file on Windows with an editor that uses \r\n as a line terminator, you should use:

mysql> LOAD DATA LOCAL INFILE '/path/pet.txt' INTO TABLE pet -> LINES TERMINATED BY '\r\n';

• Add a New record using an INSERT statement:

mysql> INSERT INTO pet -> VALUES ('Puffball','Diane','hamster','f','1999-03-30',NULL);


Entering Queries

• Here's a simple command that asks the server to tell you its version number and the current date.

• Type it in as shown here following the mysql> prompt and press Enter:

mysql> SELECT VERSION(), CURRENT_DATE; +------------+--------------+ | VERSION() | CURRENT_DATE | +------------+--------------+ | 4.1.14-Max | 2005-09-03 | +------------+--------------+ 1 row in set (0.01 sec) mysql> SELECT NOW();


Executing SQL Statements from a Text File

• Put your SQL statements in a file and then tell mysql to read its input from that file. – Create a text file text_file that contains the statements you

wish to execute.

shell> mysql db_name < text_file

• If you are running mysql, you can execute an SQL script file using the source or \. command:

mysql> source filename mysql> \. filename


Use Scripts from MySQL Prompt

CREATE TABLE Sailors(sid VARCHAR(8), sname varchar(20), age numeric,primary key (sid));

CREATE TABLE Boats(bid VARCHAR(8), bname varchar(20), color varchar(10),primary key (bid));

CREATE TABLE Reserve(sid VARCHAR(8) not null references Sailors(sid), bid varchar(8) not null references Boads(did), day date,primary key (sid, bid));


Retrieving Information from a Table

• The SELECT statement is used to pull information from a table. The general form of the statement is:

SELECT what_to_selectFROM which_tableWHERE conditions_to_satisfy;

• Selecting All Data: mysql> SELECT * FROM pet;


Selecting Particular Rows

mysql> SELECT * FROM pet WHERE name = 'Bowser';

mysql> SELECT * FROM pet WHERE birth > '1998-1-1';


Examples

mysql> SELECT * FROM pet WHERE species = 'dog' AND sex = 'f';

mysql> SELECT * FROM pet WHERE species = 'snake' OR species = 'bird';

mysql> SELECT * FROM pet WHERE (species = 'cat' AND sex = 'm') -> OR (species = 'dog' AND sex = 'f');


Selecting Particular Columns

mysql> SELECT name, birth FROM pet;

mysql> SELECT name, species, birth FROM pet-> WHERE species = 'dog' OR species = 'cat';


Sorting Rows

• To sort a result, use an ORDER BY clause.• In ascending order

mysql> SELECT name, birth FROM pet ORDER BY birth;

• In descending order

mysql> SELECT name, birth FROM pet ORDER BY birth DESC;

• You can sort on multiple columns mysql> SELECT name, species, birth FROM pet ORDER BY species, birth

DESC;

– Note that the DESC keyword applies only to the column name immediately preceding it (birth); it does not affect the species column sort order.


Counting Rows

mysql> SELECT COUNT(*) FROM pet;

mysql> SELECT owner, COUNT(*) FROM pet GROUP BY owner;

mysql> SELECT species, sex, COUNT(*) FROM pet -> WHERE species = 'dog' OR species = 'cat' -> GROUP BY species, sex;


Using More Than one Table

mysql> LOAD DATA LOCAL INFILE 'event.txt' INTO TABLE event;

mysql> SELECT pet.name,-> (YEAR(date)-YEAR(birth)) - (RIGHT(date,5)<RIGHT(birth,5)) AS age,-> remark-> FROM pet, event-> WHERE pet.name = event.name AND event.type = 'litter';

Here, YEAR() pulls out the year part of a date and RIGHT() pulls off the rightmost five characters that represent the MM-DD (calendar year) part of the date. The part of the expression that compares the MM-DD values evaluates to 1 or 0, which adjusts the year difference down a year if date occurs earlier in the year than birth.


Using More Than one Table

• Sometimes it is useful to join a table to itself, if you want to compare records in a table to other records in that same table. – For example, to find breeding pairs among your pets, you can

join the pet table with itself to produce candidate pairs of males and females of like species:

mysql> SELECT p1.name, p1.sex, p2.name, p2.sex, p1.species -> FROM pet AS p1, pet AS p2 -> WHERE p1.species = p2.species AND p1.sex = 'f' AND p2.sex = 'm';

+--------+------+--------+------+---------+ | name | sex | name | sex |species| +--------+------+--------+------+---------+ | Fluffy | f | Claws | m | cat | | Buffy | f | Fang | m | dog | | Buffy | f | Bowser| m | dog | +--------+------+--------+------+---------+

•

CSC 411/511: DBMS Design

Dr. Nan Wang CSC411_L12_MySQL24

Questions?

MySQL

Documents

Transcript of MySQL