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 –What if you want to change the appearance of the page? –What if you decide to use a different algorithm?

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

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

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

HTML_Template_IT Template html.html-template-it.phphttp://pear.php.net/manual/en/package. html.html-template-it.php Template Format: –Regular HTML –Placeholder {placeholder_name} –Block

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();

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

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

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

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.

Using SQL for Update SQL UPDATE tablename SET columnname = value,... WHERE condition Notes –value are set on all records matching the condition!

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