Download PHP and MySQL

MySQL
Using Databases
with PHP or Perl Scripts:
1
Objectives
• Advantages of using databases to store Web
data
• How to prepare a MySQL database for use with
Perl
• How to store, retrieve, and update data in a
MySQL database
Data Driven Web Pages
• Approach 1 - Global variables
– Disadvantage:
• Need to change program if data change
• Programs downstream need to change too
• Approach 2 - File
• Approach 3 - Database
3
To store data between
executions of scripts:
• You may use files:
– store customer data
• Login and password
– store page hit counts
– remember end-user preferences
– store product inventory
– Consumer survey
• Simple data structure
4
What is a database?
• A set of data organized into one or more
computer files.
• Text file: A type of database
– Using files for product inventory
– A file, password.txt, to keep passwords
• Generally the term is reserved for more
formal database systems like Access,
Oracle or MySQL.
5
Advantages of Scripts Accessing
Databases Over Scripts Using Files
• Faster access
– DB performs the search (random access) vs. Sequential
search - a line at a time in file
• Better concurrent access
• Easier changes to data and scripts
– Need not know data file format
• Increased security
– Perl scripts using files require access permissions set
for all
– DB uses separate ID and password to access
WHH
6
Comparison: file vs Database
File
Database
Access
sequential
Random Acc
Contents
Long string
Keys, values
Method
Parse
SQL
Update field
cumbersome
simple
Suitable 1:
Small files
Large files
Suitable 2:
Simple data
Complex data
Suitable 3:
Few data
Many data
7
Relational Database?
• Relational databases store data in tables
(usually more than one) with defined
relationships between the tables.
Primary
key
Product
Number
Product
Cost
Weight
Number
Avail
0
Hammer
$5.00
12
123
1
Screw Driver
$3.00
2
144
2
Wrench
$2.50
1.5
244
8
Relational Database Model
• Database: collection of tables
• Table: collection of similar records
• Record: collection of values: Faculty table
LastName
FirstName
Bdg
Room
Briscoe
Garry
HS
218
Furcy
David
HS
220
Georgiev
George
HS
217
Huen
Wing
HS
221
Naps
Thomas
HS
216
Yackel
Jonathan
HS
229
9
Relationship in Sample Database
Faculty
Courses
Num
Instructor
Time
Bdg
Room
221
Georgiev
9:10
HS
237
221
Yackel
12:40
HS
212
221
Yackel
1:50
HS
212
243
Perrie
9:10
HS
208
300
Naps
11:30
C
243
321
Huen
8:00
HS
456
346
Huen
10:20
HS
367
262
Naps
11:30
C
44
431
Perrie
1:50
HS
367
Lastname
Firstname
Bdg
Room
Briscoe
Garry
HS
218
Georgiev
George
HS
217
Huen
Wing
HS
215
Naps
Thomas
HS
216
Perrie
Andrew
HS
221
Yackel
Jonathan
HS
220
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Structured Query Language
(SQL)
• Language for extracting/modifying data
• Every table has a name
• Every field/column has a name
SHOW tables;
SELECT * FROM Faculty;
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SQL Select Statement
• Queries a database (read-only
access)
• Returns a set of records
• What are first names of faculty?
SELECT Firstname FROM Faculty;
• What classrooms are courses in?
SELECT Num, Bdg, Room FROM Courses;
12
where clause: focus the query
• When does comp sci 310 meet?
SELECT Time FROM Courses
WHERE Num = 310;
• What is Huen's teaching schedule?
SELECT Num, Time FROM Courses WHERE
Instructor = ‘Huen‘;
13
Boolean Operators in
WHERE clause
• What upper level courses is Huen teaching?
SELECT Num FROM Courses WHERE
Instructor = ‘Huen' AND Num >= 300;
• Note: Single quote for character strings. Hence
Instructor = ‘O’’Hare’
• What third-floor Halsey classrooms does the CS
department teach in?
SELECT Room FROM Courses WHERE Bdg='HS' AND
Room >= 300 AND Room < 400;
14
Queries over Multiple Tables
• If two tables appear in FROM clause,
DBMS generates cartesian product
• Use WHERE clause to "join" tables
• What are instructors’ first names for each
course?
SELECT Num, Firstname FROM Courses, Faculty
WHERE Courses.Instructor =
Faculty.Lastname
15
Duplicate Records
• Do not remove duplicates (default)
SELECT ALL Instructor FROM Courses;
SELECT Instructor FROM Courses;
• Explicitly remove duplicates
SELECT DISTINCT Instructor FROM Courses;
16
Tuple Variables
• Who shares classrooms with Huen?
• Need to use the courses table twice.
SELECT DISTINCT Instructor
FROM Courses, Courses
WHERE Bdg = Bdg
AND Room = Room
AND Instructor = ‘Huen’;
• Help, I'm confused! (…and so is the DBMS)
17
Tuple Variables
• We must differentiate between two uses of
the same table
SELECT DISTINCT x.instructor
FROM Courses x, Courses y
WHERE x.Bdg = y.Bdg
AND x.Room = y.Room
AND y.Instructor = ‘Huen’;
18
Counting
• Count the number of courses
SELECT COUNT(*) FROM Courses
• Count the number of courses in Halsey
SELECT COUNT(*) FROM Courses
WHERE Bdg = ‘HS’;
• Count the number of rooms used
SELECT COUNT(DISTINCT Room)
FROM Courses;
19
GROUP BY
• Criteria for grouping records
• How many times is each room used?
SELECT Room, COUNT(*) FROM Courses
GROUP BY Room;
• How many courses is each room
used for?
SELECT Room, COUNT( DISTINCT Num)
FROM Courses
GROUP BY Room;
20
ORDER BY
• Criteria for ordering (sorting) records
• Get the faculty members in descending order of
last name
SELECT LastName, FirstName
FROM Faculty
ORDER BY LastName DESC;
• Multiple fields can be sorted too
SELECT LastName, FirstName
FROM Faculty
ORDER BY LastName, FirstName;
21
Other Aggregate Functions
• MAX
• MIN
• SUM
All used similar to COUNT
• What is the lowest numbered course?
SELECT MIN(Num) FROM Courses;
22
Create a table
CREATE TABLE Faculty(
Lastname VARCHAR(10) NOT NULL
PRIMARY KEY,
Firstname VARCHAR(12),
Bdg VARCHAR(10),
room INT
);
23
Insert a row
INSERT INTO Faculty
VALUES
(‘Huen’, ‘Wing’, ‘HS’, 221);
• Better practice: More verbose and specific to
avoid data mismatch
INSERT INTO Faculty
(FirstName, LastName, Bdg, Room)
VALUES
(‘Wing’, ‘Huen’, ‘HS’, 221);
24
UPDATING A RECORD
UPDATE Tablename
SET fieldName1 = value1, …, fieldNameN
= valueN
WHERE criteria;
UPDATE Faculty
SET Room = 221
WHERE LastName = ‘Huen’ AND
FirstName = ‘Wing’;
25
DELETE FROM statement
• DELETE FROM TableName WHERE
criteria
DELETE FROM Faculty
WHERE LastName = ‘Wing’ AND
FirstName = ‘Huen’
26
PHP
PHP DB functions
27
1. From MySQL Console
Enter password:
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 6
Server version: 5.1.36-community-log MySQL Community Server
(GPL)
Type 'help;' or '\h' for help. Type '\c' to clear the current input
statement.
mysql>
28
1. PHP to connect to MySQL
• MySQL must be running
• Need username and password
– username = "cs346“
– password = "cs346_password“
• SYNTAX: mysql_connect(“host",
“username", “password")
• mysql_connect("localhost", "cs346",
"cs346_password")
29
<?php
$connection = mysql_connect("localhost", "cs346", "cs346_password") or
die(mysql_error());
if ($connection) {
$msg = "Connection to MySQL successful!";
}
?>
<html>
<head>
<title>MySQL Connection</title>
</head>
<body>
<?php echo "$msg"; ?>
</body>
</html>
30
Successful connection
31
Username or password does
not match
32
2. List DB- From MySQL Console
mysql> show databases;
+--------------------+
| Database
|
+--------------------+
| information_schema |
| books
|
| cs346
|
| mailinglist
|
| mysql
|
| products
|
+--------------------+
6 rows in set (0.02 sec)
mysql>
33
2. PHP listing databases
34
Some useful functions
• mysql_list_dbs() - used to list the
databases on a MySQL server
• mysql_num_rows() - returns the number of
rows in a result set
• mysql_tablename() - Though the name
implies tablename only, it extracts names
of tables, or databases from a result set
35
<?php
$connection = @mysql_connect("localhost", "cs346",
"cs346_password") or die(mysql_error());
$dbs = @mysql_list_dbs($connection)or die(mysql_error());
$db_list ="<ul>";
$i =0;
while ($i < mysql_num_rows($dbs)){
$db_names[$i] = mysql_tablename($dbs,$i);
/* mysql_tablename(list_as_table, row_index) */
$db_list .= "<li>$db_names[$i]</li>"; // concatentation
$i++;
}
$db_list .="</ul>";
?>
36
<html>
<head>
<title>MySQL Databases</title>
</head>
<body>
<p><strong>Databases on localhost</strong>:</p>
<?php echo "$db_list"; ?>
</body>
</html>
37
3. Show tables - from MySQL Console
mysql> use books;
Database changed
mysql> show tables;
+-----------------+
| Tables_in_books |
+-----------------+
| authorisbn
|
| authors
|
| titles
|
+-----------------+
3 rows in set (0.13 sec)
38
mysql> use cs346;
Database changed
mysql> show tables;
+-----------------+
| Tables_in_cs346 |
+-----------------+
| movies
|
+-----------------+
1 row in set (0.28 sec)
mysql>
39
3. List tables - PHP
• MySQL Console:
– use <database_name>;
– Show tables;
– One DB at a time
• PHP:
– mysql_list_tables function
– Use nested while loops
– See 11-2db_listtables.php
40
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42
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4. Create database – from MySQL Console
mysql> create database testDB;
Query OK, 1 row affected (0.19 sec)
mysql> show databases;
+--------------------+
| Database
|
+--------------------+
| information_schema |
| books
|
| cs346
|
| mailinglist
|
| mysql
|
| products
|
| testdb
|
+--------------------+
7 rows in set (0.01 sec)
mysql>
44
5. Drop database – from MySQL console
mysql> drop database testdb;
Query OK, 0 rows affected (0.27 sec)
mysql> show databases;
+--------------------+
| Database
|
+--------------------+
| information_schema |
| books
|
| cs346
|
| mailinglist
|
| mysql
|
| products
|
+--------------------+
6 rows in set (0.00 sec)
mysql>
45
4. PHP to create DB
• $sql_string = “create database testDB2”;
• $connection =
@mysql_connect("localhost",“username",
“password") or die(mysql_error());
• mysql_query($sql_string,$connection) or
die(mysql_error());
46
What happened?
47
Perhaps cs346 has no permission to create
mysql> select user, select_priv, insert_priv,
create_priv from user;
+-------+-------------+-------------+-------------+
| user | select_priv | insert_priv | create_priv |
+-------+-------------+-------------+-------------+
| root | Y
| Y
| Y
|
| root | Y
| Y
| Y
|
| huen | Y
| Y
| Y
|
| cs346 | Y
| Y
| N
|
+-------+-------------+-------------+-------------+
4 rows in set (0.00 sec)
48
Admin needs to grant permissions
mysql> GRANT CREATE on *.* TO 'cs346'@localhost;
Query OK, 0 rows affected (0.00 sec)
mysql> select user, select_priv, insert_priv,
create_priv from user;
+-------+-------------+-------------+-------------+
| user | select_priv | insert_priv | create_priv |
+-------+-------------+-------------+-------------+
| root | Y
| Y
| Y
|
| root | Y
| Y
| Y
|
| huen | Y
| Y
| Y
|
| cs346 | Y
| Y
| Y
|
+-------+-------------+-------------+-------------+
4 rows in set (0.00 sec)
mysql>
49
Now test again
50
Run 11-2db_listdb.php
51
5. PHP to drop DB
• $sql_string = “drop database testDB2”;
• $connection =
@mysql_connect("localhost",“username",
“password") or die(mysql_error());
• mysql_query($sql_string,$connection) or
die(mysql_error());
52
Run 11-5db_dropdb.php
53
Admin to grant cs346 limited drop permissions
mysql> GRANT DROP ON testdb2.* TO 'cs346'@localhost;
Query OK, 0 rows affected (0.08 sec)
mysql> select user, drop_priv from user;
+-------+-----------+
| user | drop_priv |
+-------+-----------+
| root | Y
|
| root | Y
|
| huen | Y
|
| cs346 | N
|
+-------+-----------+
4 rows in set (0.00 sec)
Note still drop_priv == N
54
Run 11-5db_dropdb.php again
55
Run 11-2db_listdb.php
56
Create tables
And insert values
57
First create a DB with db_createdb.php
58
List DB
59
From Admin
• Create table my_music
– Specify the fields and type
• Insert values into the table
– Either interactively or
– By batch – use source command
60
Use PHP
• 12-1show_createtable.html – form to enter
– table name
– number of attributes
– Call PHP script to show field definitions
• 12-1do_showfielddef.php - form to enter
– Field name
– Field type
– Field length
• 12-1do_createtable.php
61
12-1show_createtable.html
62
12-1do_showfielddef.php
63
On clicking the submit
64
Confirm table my_music in 2 ways
• From Admin
– Show databases;
– Use testdb1;
– Show tables;
– Describe my_music
• From PHP:
– 11-3db_listtables.php
– Use mysql_query($sql,$connection) where
$sql = ‘describe my_music’
65
mysql> use testdb1;
Database changed
mysql> show tables;
+-------------------+
| Tables_in_testdb1 |
+-------------------+
| my_music
|
+-------------------+
1 row in set (0.00 sec)
mysql> describe my_music;
66
mysql> describe my_music;
+-----------+--------------+------+-----+---------+-------+
| Field
| Type
| Null | Key | Default | Extra |
+-----------+--------------+------+-----+---------+-------+
| id
| int(5)
| YES |
| NULL
|
|
| format
| char(2)
| YES |
| NULL
|
|
| title
| varchar(150) | YES |
| NULL
|
|
| artist_fn | varchar(100) | YES |
| NULL
|
|
| artist_ln | varchar(100) | YES |
| NULL
|
|
| rec_label | varchar(50) | YES |
| NULL
|
|
| my_notes | text
| YES |
| NULL
|
|
| date_acq | date
| YES |
| NULL
|
|
+-----------+--------------+------+-----+---------+-------+
8 rows in set (0.00 sec)
mysql>
67
68
Insert values
Locally (Admin) and remotely
(PHP)
69
PHP to add record
• 13-1show_addrecord.html
– Use a form to enter the field values
– Submit the info to a PHP script
• 13-1do_addrecord.php
70
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Check
• From MySQL Console
mysql> select id, title, date_acq from my_music;
+------+-----------------------------------+------------+
| id
| title
| date_acq
|
+------+-----------------------------------+------------+
|
1 | Pomp and Circumstance March No. 1 | 2005-06-19 |
|
2 | The Four Seasons: Vivaldi
| 2006-07-20 |
+------+-----------------------------------+------------+
2 rows in set (0.00 sec)
mysql>
• PHP script:
– mysql_query($sql,$connection)or
die(mysql_error());
75
Displaying Data in DB
--- really it is via Select query
76
Display Info in DB
• Html for selecting by id, artist, date, etc.
• Different PHP scripts to send query
77
14-1my_menu.html
78
Ordered by ID
79
Ordered by Date Acquired
80
Ordered by Title
81
Ordered by Artist
82
Perl
Perl DB functions
83
Some DB entry aid
• db_accessU.cgi, interactive GUI
– One SQL statement at a time
• Create a script to enter multiple SQL
statements in a batch
My @sql = (
‘DROP TABLE ingredient;’
‘CREATE TABLE ingredient (
id VARCHAR(32) NOT NULL PRIMARY KEY,
amt INTEGER UNSIGNED);’
“INSERT INTO ingredient VALUES(‘flour’,1);”
)
84
Connect, query, disconnect
• Both db_accessU.cgi and a batch
script need to
– ‘Connect’ to a database by logging
in with username and password
– ‘prepare’ a query
– ‘execute’ the query
– ‘fetch a row’ from the specified
table
– ‘disconnect’ from the database
85
Perl Database Interface DBI
Use DBI
– Object-oriented interface
• Driver Handle
– Encapsulates the driver for the database
• Database handle
– Encapsulates a specific connection to a database;
can send SQL statements to a database
• Statement handle
– Encapsulates specific SQL statements and the results
returned from them
86
Connection to DB
use DBI;
# load DBI.pm
use DBD::mysql;
# Load the DB Driver
If( $db_handle = DBI -> connect
(“DBI:mysql:$dbName:$opt_host”,
“username”, “password”) )
{ # print success
87
prepare and execute query
# prepare the query
if( $stmt_handle = $db_handle ->
prepare($sqlstmt) )
print ‘Success’;
# execute the query
if( $stmt_handle -> execute())
print “Success”;
88
Fetch a row from table
While ( @row = $stmt_handle ->
fetchrow_array())
{ # process the row
}
89
Disconnect from DB
$db_handle -> disconnect();
90