Transcript MySQL - Education Scotland

Relational Database Systems
Higher Information Systems
Advanced Implementation in
MySQL/PHP
Developing a solution
Tables
 Queries
 User Views
 Navigation
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Introducing SQL
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Relational database management
systems (RDBMSs) are based on a data
definition language called Structured
Query Language or SQL (often
pronounced “sequel”).
MySQL takes its name from SQL.
Introducing SQL
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SQL is a data definition language
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CREATE DATABASE `DVD Rentals`
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CREATE TABLE Member(
`Member Number` integer,
Name varchar(30),
Address varchar(50),
`Post Code` varchar(7),
`Telephone Number` varchar(11))
Introducing SQL
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SQL is also a data manipulation language
INSERT INTO Member
VALUES (`233`, `Jo Soap`, `1 Getting Close`,
`IS99 2QZ`, `123456`)
SELECT * FROM Member
WHERE `Member Number` BETWEEN 1 and 250
ORDER BY `Member Number` DESC
DELETE FROM Member
WHERE `Member Number` > 500
phpMyAdmin
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A graphical user interface for MySQL
phpMyAdmin
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Viewing a table definition
phpMyAdmin
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Adding a record
phpMyAdmin
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Selecting records
phpMyAdmin
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Viewing selected records
phpMyAdmin
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Viewing selected records
Referential Integrity
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For the database to work properly, it is
essential to guarantee that a foreign key
always refers to a record which exists in the
other table.
This is called referential integrity.
For example, an entry in the Loan table can
only refer to an existing record in the Member
table, because a loan can only be made by a
member.
Referential Integrity
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MySQL has no internal facility to maintain
referential integrity (with the default MyISAM
table type) - instead, the database’s interface
must be designed in such a way that a check
is made on any value entered to ensure it is
valid.
Usually this is done by using a list on a web
page to display the available choices for a
field value from which the user may make a
selection.
Validation: Presence Check
Validation: Range Check
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Range checking is performed by the
interface
Use PHP scripting to check numeric
values
Validation: Restricted Choice
Check
Validation: Default Value
Formatting
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All formatting of data for output is done
using PHP functions
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e.g. printf
Queries
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Searching
Sorting
Calculations
All searching, sorting and calculation
queries are performed using an SQL
expression string
Searching
Searching is the process of selecting records
from a table or combination of tables.
To perform the query, three items must be
identified:
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Which fields will be used to identify the records
required?
Which tables are required to produce the data
required?
What are the criteria for identifying the records
required?
Search 1: Single Condition
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Identify the names and telephone
numbers of club members with Member
Number over 1000
SELECT FORENAME, SURNAME,
`TELEPHONE NUMBER`
FROM MEMBER
WHERE `MEMBER NUMBER` > 1000
Search 1: Single Condition
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The asterisk * symbol can be used in an
expression string to extract all fields
from a table
SELECT *
FROM MEMBER
WHERE `MEMBER NUMBER` > 1000
Search 2:
Multiple Conditions (AND)
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Identify the names and telephone numbers of
club members with Surnames beginning with
M and Member Number over 1000
SELECT FORENAME, SURNAME,
`TELEPHONE NUMBER`
FROM MEMBER
WHERE SURNAME LIKE “M*” AND
`MEMBER NUMBER` > 1000
Search 3:
Multiple Conditions (OR)
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Identify the names and telephone
numbers of club members with
Surnames beginning with M or N
SELECT FORENAME, SURNAME,
`TELEPHONE NUMBER`
FROM MEMBER
WHERE SURNAME LIKE “M*” OR
SURNAME LIKE “N*”
Search 4: More than one table
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Identify the names of club members who rented a
DVD in August 2005
In order to extract the related records from each
table, a join operation is performed in SQL
This will combine those records from each table
which have a corresponding record in the other table
into a single set of related records (called an answer
set)
The keyword used to perform this is INNER JOIN
Search 4: More than one table
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Identify the names of club members who
rented a DVD in August 2005
SELECT FORENAME, SURNAME, `DATE
HIRED`
FROM (MEMBER INNER JOIN LOAN) ON
`MEMBER.MEMBER
NUMBER`=`LOAN.MEMBER NUMBER`
WHERE `DATE HIRED` LIKE “*/8/2005”
Search 5:
More than two tables
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Identify the names of members who
have rented “Shrek”
This time all four tables are required:
Member, Loan, DVD and Film.
A nested INNER JOIN statement must
be performed to combine these
together into a single answer set
Search 5:
More than two tables
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Identify the names of members who have rented
“Shrek”
SELECT `FORENAME`, `SURNAME`, `TITLE`
FROM
(((MEMBER INNER JOIN LOAN
ON MEMBER.MEMBER NUMBER=LOAN.MEMBER
NUMBER)
INNER JOIN DVD
ON LOAN.DVD CODE = DVD.DVD CODE)
INNER JOIN FILM
ON DVD.FILM CODE = FILM.FILM CODE)
WHERE `TITLE` = “SHREK”
Search 6:
Dealing with duplicates
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List those members who have rented “Shrek”
or “Finding Nemo”
SELECT `FORENAME`, `SURNAME`, `TITLE`
FROM (((MEMBER INNER JOIN LOAN
ON MEMBER.MEMBER NUMBER=LOAN.MEMBER NUMBER)
INNER JOIN DVD
ON LOAN.DVD CODE = DVD.DVD CODE)
INNER JOIN FILM
ON DVD.FILM CODE = FILM.FILM CODE)
WHERE `TITLE` = “SHREK” OR `TITLE` = “FINDING NEMO”
Search 6:
Dealing with duplicates
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The Group By option is used to eliminate
duplicate results
SELECT `FORENAME`, `SURNAME`, `TITLE`
FROM (((MEMBER INNER JOIN LOAN
ON MEMBER.MEMBER NUMBER=LOAN.MEMBER NUMBER)
INNER JOIN DVD
ON LOAN.DVD CODE = DVD.DVD CODE)
INNER JOIN FILM
ON DVD.FILM CODE = FILM.FILM CODE)
WHERE `TITLE` = “SHREK” OR `TITLE` = “FINDING NEMO”
GROUP BY *
Sorting
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To perform a sort, two items must be
identified:
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Which field (or fields) will be used to
decide the order of records?
For each field selected, will the order of
sorting be ascending or descending?
Sorting
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To produce a list of people with the tallest
first, the records would be sorted in
descending order of height.
To produce a list of people with youngest
first, the records would be sorted in
ascending order of age.
A very common way of ordering records
relating to people is in alphabetical order. To
achieve alphabetical ordering requires the
records to be sorted in ascending order of
surname.
Complex Sorting
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A complex sort involves more than one sort
condition involving two or more fields.
To achieve “telephone book order”, the name
is sorted in ascending order of surname, then
ascending order of forename. In this case,
the Surname field is the primary sort key,
and the Forename field is the secondary
sort key.
Sorting
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SELECT FORENAME, SURNAME
FROM MEMBER
WHERE `MEMBER NUMBER` > 1000
ORDER BY SURNAME, FORENAME
SELECT FORENAME, SURNAME
FROM MEMBER
WHERE `MEMBER NUMBER` > 1000
ORDER BY `MEMBER NUMBER` DESC
Calculations
Name
Test Test Test
1
2
3
record 1
J Bloggs
8
9
10
record 2
J Public
6
7
8
7
8
9
vertical
calculations
Total
Mark
27
horizontal
21 calculations
Average
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Horizontal calculations are often known as
calculated fields, and vertical calculations are
known as summary fields.
Functions (MySQL)
Category
Example of functions
Aggregate
MySQL: SUM, AVG, MAX, MIN, COUNT
Mathematical MySQL: SIN, COS, TAN, TRUNCATE, ROUND
Text
MySQL: LEFT, RIGHT, SUBSTRING, LENGTH, LOWER, UPPER,
LOCATE, REPLACE
Logical
MySQL: IF, IFNULL
Conversion
MySQL: FORMAT, CONVERT, DATEF_ORMAT, STR_TO_DATE
Date
MySQL: CURDATE, DATEFORMAT, DAYOFMONTH, DAYOFWEEK,
DAYNAME, MONTH, MONTHNAME, DATEDIFF, DATE_SUB
Time
MySQL: CURTIME, HOUR, MINUTE, SECOND, TIMEDIFF
Functions (PHP)
Category
Example of functions
Aggregate
Mathematical PHP: Sin, Cos, Tan, Floor, Round
Text
PHP: SubStr, StrLen, StrToUpper, StrToLower, StrPos,
SubStr_Replace
Logical
PHP: If, While, For, Foreach, Switch
Conversion
PHP: StrToTime
Date
PHP: GetDate, Date
Time
PHP: GetTimeOfDay, StrFTime
Working with Dates
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to search for all DVDs rented in the last week,
you would use the expression
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SELECT * FROM LOAN WHERE
DATEDIFF(CURDATE(),`DATE HIRED`) < 7
to calculate a person’s age in years from their
date of birth, you would use the expression
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SELECT (YEAR(CURDATE()) – YEAR(`DATE OF
BIRTH`) –
(RIGHT(CURDATE(),5)<RIGHT(`DATE OF
BIRTH`,5)) AS AGE
Parameterised Queries
1 <form action="<?=$PHP_SELF?>" method="post">
2
<p>Enter the date required:<br />
3
<input type="text" name="searchdate"><br />
4
<input type="submit" name="submitsearch" value="SUBMIT" />
5
</p>
6 </form>
7
8 <?php
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if ($submitsearch == "SUBMIT") {
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$sql = "SELECT `MEMBER NUMBER`
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WHERE `DATE HIRED` = $searchdate";
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if (@mysql_query($sql)) {
13
…
User Views
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User views are created using forms and
reports.
A form or report is usually based on a query
which selects the required fields from the
appropriate tables, sorting the results if
necessary, and performing any horizontal
calculations.
In a MySQL application, all output is generally
in the form of a web page.
Report Structure
Report
Header
Text/data/data to appear at the head of
the report
Page Header
Text/data to appear at the top of each
page of the report
Main Detail
Header
Text/data to appear above each entry in
the main detail section
Main Detail
Section
DVD Rental
Statistics
Page 1
Details for J Bloggs
Memb No Address
Tel No
Data from selected records in a table or
query
142312
123456
Main Detail
Footer
Text/data to appear below each entry in
the main detail section
Total DVDs rented to date: 26
Page Footer
Text/data to appear at the foot of each
page of the report
Report
Footer
Text/data to appear at the bottom of the
report
Main Street
End of page 1
Total DVDs rented by all members:
3,218
Summary Information
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Sum
to add values to give a total, e.g. Total
Cost of DVD Rentals last month
Average to find an average value, e.g. Average
Cost of Hire per DVD
Count
to count the number of records found,
e.g. Number of DVDs rented per member
Maximum to find the highest value, e.g.
Highest number of rentals per DVD (to
find the most popular DVD)
Minimum to find the lowest value, e.g. Lowest
number of rentals per member
Summary Information
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In a MySQL application, the aggregate
functions SUM, AVG, COUNT, MAX and MIN
can be used in an SQL expression string to
produce summary information for a set of
extracted records
However, certain summary information, such
as page totals, would have to be programmed
using PHP (e.g. counting the number of
records being displayed)
Scripting
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In a MySQL application, all navigation and
user interface features are implemented
using scripting
$result = @mysql_query("SELECT Forename, Surname FROM
Member");
while ( $row = mysql_fetch_array($result) ) {
$forename = $row["Forename"];
$surname = $row["Surname"];
echo("<tr><td>$forename</td><td>$surname</td></tr>");
}
Macros