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Web Database Programming Week 6

Web Database Programming Week 6. Using Templates & Updating Web Database. 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

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Web Database Programming Week 6

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  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-template-it.php • Template Format: • Regular HTML • Placeholder {placeholder_name} • Block <!-- BEGIN block_name --> <!-- END block_name -->

  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->loadTemplatefile(“template_filename”, true, true); $template->setCurrentBlock(“block_name”); $template->setVariable(“placeholder_name”, data); $template->parseCurrentBlock(); $template->show();

  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 type=hidden 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

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