Relational Database SystemsHigher Information Systems

Advanced Implementation in MySQL/PHP

Developing a solutionTablesQueriesUser ViewsNavigation

Introducing SQLRelational 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 SQLSQL is a data definition languageCREATE DATABASE `DVD Rentals`CREATE TABLE Member( `Member Number` integer, Name varchar(30), Address varchar(50), `Post Code` varchar(7), `Telephone Number` varchar(11))

Introducing SQLSQL 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` DESCDELETE FROM Member WHERE `Member Number` > 500

phpMyAdminA graphical user interface for MySQL

phpMyAdminViewing a table definition

phpMyAdminAdding a record

phpMyAdminSelecting records

phpMyAdminViewing selected records

phpMyAdminViewing selected records

Referential IntegrityFor 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 IntegrityMySQL has no internal facility to maintain referential integrity (with the default MyISAM table type) - instead, the databases 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 CheckRange checking is performed by the interfaceUse PHP scripting to check numeric values

Validation: Restricted Choice Check

Validation: Default Value

FormattingAll formatting of data for output is done using PHP functionse.g. printf

QueriesSearchingSortingCalculationsAll searching, sorting and calculation queries are performed using an SQL expression string

SearchingSearching is the process of selecting records from a table or combination of tables. To perform the query, three items must be identified: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 ConditionIdentify 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 ConditionThe 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)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)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 tableIdentify 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 SQLThis 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 tableIdentify 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 tablesIdentify 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 tablesIdentify 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 duplicatesList those members who have rented Shrek or Finding NemoSELECT `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 duplicatesThe 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 *

SortingTo perform a sort, two items must be identified: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?

SortingTo 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 SortingA 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.

SortingSELECT FORENAME, SURNAME FROM MEMBER WHERE `MEMBER NUMBER` > 1000 ORDER BY SURNAME, FORENAMESELECT FORENAME, SURNAME FROM MEMBER WHERE `MEMBER NUMBER` > 1000 ORDER BY `MEMBER NUMBER` DESC

CalculationsHorizontal calculations are often known as calculated fields, and vertical calculations are known as summary fields.

Name

Test 1

Test 2

Test 3

Total Mark

record 1

J Bloggs

8

9

10

27

horizontal calculations

record 2

J Public

6

7

8

21

Average

7

8

9

vertical calculations

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 Datesto search for all DVDs rented in the last week, you would use the expressionSELECT * FROM LOAN WHERE DATEDIFF(CURDATE(),`DATE HIRED`) < 7to calculate a persons age in years from their date of birth, you would use the expressionSELECT (YEAR(CURDATE()) YEAR(`DATE OF BIRTH`) (RIGHT(CURDATE(),5)

Parameterised Queries

1

2

3

4

5

6

7

8

9

10

11

12

13

User ViewsUser 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

DVD Rental Statistics

Page Header

Text/data to appear at the top of each page of the report

Page 1

Main Detail Header

Text/data to appear above each entry in the main detail section

Details for J Bloggs

Memb NoAddressTel No

Main Detail Section

Data from selected records in a table or query

142312Main Street123456

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

End of page 1

Report Footer

Text/data to appear at the bottom of the report

Total DVDs rented by all members: 3,218

Summary InformationSumto add values to give a total, e.g. Total Cost of DVD Rentals last monthAverageto find an average value, e.g. Average Cost of Hire per DVDCountto count the number of records found, e.g. Number of DVDs rented per memberMaximumto find the highest value, e.g. Highest number of rentals per DVD (to find the most popular DVD)Minimumto find the lowest value, e.g. Lowest number of rentals per member

Summary InformationIn 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 recordsHowever, certain summary information, such as page totals, would have to be programmed using PHP (e.g. counting the number of records being displayed)

ScriptingIn 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 = $row["Surname"]; echo("$forename$surname");}

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