Web Database Programming Week 6

1
Web Database Programming Week 6

• Using Templates
• Updating Web Database

2
PHP HTML

• PHP code can be inserted anywhere in HTML code
• PHP code can output any HTML code
• Tightly mixed code (e.g. our sample code)
• Hard to read
• Hard to maintain
• What if you want to change the appearance of the
  page?
• What if you decide to use a different algorithm?

3
Separate Presentation and Processing

• An important user interface design principle
• Easy to change interface or backend processing
  independently
• Easier maintenance
• Reusable code
• How?
• Using templates

4
Template

• Define HTML presentation
• Placeholders
• To be filled with data from PHP code
• Extensions to PHP
• Smarty
• PEAR Integrated Template

5
PEAR

• PHP Extension and Application Repository
• Includes many packages
• DB, HTML_Template_IT, Authentication, Encryption,
  Graphics, XML, SOAP
• Core packages comes with PHP 4.3.0 later
• Optional packages needs to be installed

6
HTML_Template_IT Template

• http//pear.php.net/manual/en/package.html.html-te
  mplate-it.php
• Template Format
• Regular HTML
• Placeholder
• placeholder_name
• Block
• lt!-- BEGIN block_name --gt
• lt!-- END block_name --gt

7
HTML_Template_IT Class

• Use the class
• require_once HTML/Template/IT.php
• Create the object
• template new HTML_Template_IT(template_dir)
• Call the methods
• template-gtloadTemplatefile(template_filename,
  true, true)
• template-gtsetCurrentBlock(block_name)
• template-gtsetVariable(placeholder_name, data)
• template-gtparseCurrentBlock()
• template-gtshow()

8
Update Database

• Table Operations
• Create table structure
• Change table structure
• Delete table
• Record Operations
• Insert a record to a table
• Update a record
• Delete a record

9
Making an Insert Form

• Example
• Notes
• Recall that PHP will convert form field names
  into variables in the action page
• use input typehidden to set predefined and
  previously fixed values (like foreign keys) and
  to carry values forward

10
Using SQL for Insert

• SQL
• INSERT INTO tablename (columnnames)
• VALUES (values)
• Note
• value do not have to come from form they could,
  for example, be computed, or taken from another
  query
• Remember single quote for text values and not
  for numbers

11
An Update Form

• Example
• Notes
• note the addition of a record ID value (which we
  must get from somewhere!) tells us which record
  we are updating.

12
Using SQL for Update

• SQL
• UPDATE tablename
• SET columnname value, ...
• WHERE condition
• Notes
• value are set on all records matching the
  condition!

13
Deleting data from a table

• The form for the SQL part of the code is
• DELETE FROM tablename
• WHERE condition
• Note
• all records matching the condition are deleted
• if there is no where clause deletes all records
  in table