Creating PHPs to Insert, Update, and Delete Data CS 320

Approach For Inserting Data Create first page (HTML or PHP) to collect user inputs using an HTML form  Passes inputs as parameters to the second page Create second page (PHP) to execute the INSERT query and display appropriate response (success or failure) depending on the query outcome  Tip: write the insert query with its values hard coded before trying to write it using the values the user submits

Inserting New Data insert succeeds insert fails Page 1 ProductInput.html Page 2 ProductInsert.php *Complete HTML and PHP pages are available in D2L

Review: Web Tag Attributes Name: identifies the form internally within the Web page Action: specifies the action the Web server performs with the form parameter list  Usually specifies a script or program that runs on the Web server Method: how the Web server processes the parameters  GET: passes the parameters as a list on the URL  POST: sends the parameters directly to the receiving program

GET and POST Parameter Passing GET: passes the parameters as a list in the URL POST: sends the parameters directly to the receiving program without displaying them in the URL Strategy:  Use GET while you are developing PHP pages  Switch to POST when you are ready to deploy the pages Parameters Action

Review: Web form input name attributes Specifies how a parameter value passed by a Web form is referenced in the server program  Good idea: give the inputs the same names as the corresponding database fields

Referencing Form Parameters in PHPs General syntax: Specific example:  The name you give to a form’s input in the previous page is what you use for form_parameter_name in $_REQUEST $_REQUEST["parameter_name"]

Referencing Form Parameters in PHPs Remember that the parameter is coming from the page that calls the current page: Code in InsertProduct.php:

Steps for Inserting Data Using a PHP 1. Receive input parameters and assign them to variables 2. Create the query 3. Execute the query  If it fails, display the failure message  Otherwise, display the success message (good idea to redisplay the table records also)

PHP With INSERT Command <?php //Put code here to connect to MySQL and specify the database //assign the parameter values to variables $prod_desc = $_REQUEST['prod_desc']; $prod_cost = $_REQUEST['prod_cost']; $prod_price = $_REQUEST['prod_price']; //Specify the query $query = "INSERT INTO candy_product (prod_desc, prod_cost, prod_price) ". "VALUES ('$prod_desc',$prod_cost,$prod_price)"; //Execute the query $result = mysql_query($query) //Show alternate failures message when you are done with development or die("SQL Error: ". mysql_error(). " "); //Display success message echo $msg = "Record successfully inserted"; //Add code here to retrieve and display CANDY_PRODUCT table contents //so user can see result of insert ?> Character data type must be in single quotes Concatenation operator to show INSERT command on multiple lines From InsertProduct.php

Updating Data Page 1: ProductList.php Select record to update Page 3: UpdateProduct.php Confirmation (show message, updated product information or error message) Page 2: ViewProductRecord.php Display single record layout for selected record Passes selected prod_id as parameter Passes prod_id and updated values

Displaying retrieved data values in selection list: <?php $query = "SELECT prod_id, prod_desc FROM candy_product"; $result = mysql_query($query) or die("SQL Error: ". mysql_error(). " "); ?> Select a product for updating: "> From ProductList.php

Displaying retrieved values in form inputs: Receive the prod_id value as a parameter and store it as a variable Create a new form and specify prod_id as a hidden input Retrieve the current values for the selected prod_id's other values Create text inputs whose values are the current prod_id record values See: ViewProductRecord.php

Save prod_id parameter as a variable and retrieve current product values: <?php //save passed parameter as a variable $prod_id = $_REQUEST['prod_id']; //Specify the query $query = "SELECT prod_desc, prod_cost, prod_price FROM candy_product ". "WHERE prod_id = $prod_id"; //Store the result $result = mysql_query($query) or die("SQL Error: ". mysql_error(). " "); ?> From ViewProductRecord.php

Create a form, add prod_id as a hidden form input, display other values as form text input values: Update Product Information " /> Description: " type="text" size="30" maxlength="30" /> Cost: " Price: " /> From ViewProductRecord.php

Update the CANDY_PRODUCT table and display success message //save passed parameters as variables $prod_id = $_REQUEST['prod_id']; $prod_desc = $_REQUEST['prod_desc']; $prod_cost = $_REQUEST['prod_cost']; $prod_price = $_REQUEST['prod_price']; //Create UPDATE query $query = "UPDATE candy_product ". "SET prod_desc = '$prod_desc', ". "prod_cost = $prod_cost, ". "prod_price = $prod_price ". "WHERE prod_id = $prod_id"; //Execute the query $result = mysql_query($query) or die("SQL Error: ". mysql_error(). " "); //Display page content echo $msg = "Record successfully updated"; //Add code to retrieve and display CANDY_PRODUCT table contents //here so user can see result of update From UpdateProduct.php Place character data type value in single quotes

Selecting Data Using a Hyperlink Table Page 1: Product_Hyperlink_Table.php Page 3: UpdateProduct.php Confirmation (show message, updated product information or error message) Page 2: ViewProductRecord.php Display single record layout for selected record

Deleting Data From a business standpoint, be very cautious about allowing users to delete data  Better to archive You can't delete parent records that are referenced as foreign keys

Deleting Data Delete succeeds Delete fails Page 1 ProductListDelete.html Page 2 ProductDelete.php

PHP With DELETE Command <?php //Put code here to connect to MySQL and specify the database //save passed parameter as variable $prod_id = $_REQUEST['prod_id']; //Create DELETE query $query = "DELETE FROM candy_product ". "WHERE prod_id = $prod_id"; //Execute the query $result = mysql_query($query) or die("SQL Error: ". mysql_error(). " "); //Display page content echo $msg = "Record successfully deleted"; //Add code to retrieve and display CANDY_PRODUCT table contents //here so user can see result of delete From ProductDelete.php

PHP/Database Debugging Strategies Develop incrementally!  Add one line of code  Test  Repeat Use method="GET" to view parameter names and values View the page source code  Make sure you are testing the most current version of your PHP page Display SQL queries directly on the Web page  Then run the query in MySQL Query Workbench

To debug a query, comment out all other code and display it on the Web page: <?php //Put code here to connect to MySQL and specify the database //assign the parameter values to variables $prod_desc = $_REQUEST['prod_desc']; $prod_cost = $_REQUEST['prod_cost']; $prod_price = $_REQUEST['prod_price']; //Specify the query $query = "INSERT INTO candy_product (prod_desc, prod_cost, prod_price) ". "VALUES ('$prod_desc',$prod_cost,$prod_price)"; //Store the result //$result = mysql_query($query) //Show alternate failures message when you are done with development //or die("SQL Error: ". mysql_error(). " "); //Display success message //echo $msg = "Record successfully inserted"; echo $query ?>

Additional PHP Resources Tutorials  Basic PHP  MySQL Search Google for specific topics…