first, you send a query template to the MySQL server, using placeholders (as ?) instead of values (lines 10-14 of the above example).Instead of building a complete query string with the escaped values, using prepared statements is a three-steps process: Prepared statements are a bit more complex than escaping. $orders_ai = 'ALTER TABLE `order_products` MODIFY `id` int(10) UNSIGNED NOT NULL AUTO_INCREMENT' $orders_pk = 'ALTER TABLE `order_products` ADD PRIMARY KEY (`id`)' * If there is an error an exception is thrown */ Now let’s create the last table, order_products. If the return value is either true or a result resource (which also evaluates to true), it means that the query was executed successfully. In the above example, you check if the result is false and, in that case, you output the error message and terminate the script. A resource if the query succeeded and returned a result set (like when reading rows from a table).true if the query succeeded without returning a result (like in this case).The return value from mysql_query() or from MySQLi::query() can be: You did that when connecting, and you should do every time you execute a query too. When you work with databases, it’s important that you always check for errors. Remember? It’s the variable returned by the mysqli_connect() function inside your db_inc.php connection script. Note that mysqli_query() requires the mysqli connection resource as first argument. The mysqli_query() function and the MySQLi::query() class method execute an SQL query (or SQL statement). * if mysqli::query() returns FALSE it means an error occurred */Įcho 'Orders table created successfully' If (!mysqli_query($mysqli, $products_ai)) * if mysqli_query() returns FALSE it means an error occurred */Įcho 'Query error: '. If (!mysqli_query($mysqli, $products_pk)) $order_products_ai = 'ALTER TABLE `order_products` MODIFY `id` int(10) UNSIGNED NOT NULL AUTO_INCREMENT' $order_products_pk = 'ALTER TABLE `order_products` ADD PRIMARY KEY (`id`)' $orders_ai = 'ALTER TABLE `orders` MODIFY `id` int(10) UNSIGNED NOT NULL AUTO_INCREMENT' $orders_pk = 'ALTER TABLE `orders` ADD PRIMARY KEY (`id`)' $products_ai = 'ALTER TABLE `products` MODIFY `id` int(10) UNSIGNED NOT NULL AUTO_INCREMENT' $products_pk = 'ALTER TABLE `products` ADD PRIMARY KEY (`id`)' If the original statement template is not derived from external input, SQL injection cannot occur./* Query #1: create the table structure */ Prepared statements are very useful against SQL injections, because parameter values, which are transmitted later using a different protocol, need not be correctly escaped.Bound parameters minimize bandwidth to the server as you need send only the parameters each time, and not the whole query.Prepared statements reduce parsing time as the preparation on the query is done only once (although the statement is executed multiple times).The application may execute the statement as many times as it wants with different valuesĬompared to executing SQL statements directly, prepared statements have three main advantages: Execute: At a later time, the application binds the values to the parameters, and the database executes the statement.The database parses, compiles, and performs query optimization on the SQL statement template, and stores the result without executing it.

Example: INSERT INTO MyGuests VALUES(?, ?, ?) Certain values are left unspecified, called parameters (labeled '?'). Prepare: An SQL statement template is created and sent to the database.Prepared statements basically work like this: Statements repeatedly with high efficiency. Prepared statements are very useful against SQL injections.Ī prepared statement is a feature used to execute the same (or similar) SQL PHP Examples PHP Examples PHP Compiler PHP Quiz PHP Exercises PHP Server PHP Certificate PHP - AJAX AJAX Intro AJAX PHP AJAX Database AJAX XML AJAX Live Search AJAX Poll PHP XML PHP XML Parsers PHP SimpleXML Parser PHP SimpleXML - Get PHP XML Expat PHP XML DOM MySQL Database MySQL Database MySQL Connect MySQL Create DB MySQL Create Table MySQL Insert Data MySQL Get Last ID MySQL Insert Multiple MySQL Prepared MySQL Select Data MySQL Where MySQL Order By MySQL Delete Data MySQL Update Data MySQL Limit Data PHP OOP PHP What is OOP PHP Classes/Objects PHP Constructor PHP Destructor PHP Access Modifiers PHP Inheritance PHP Constants PHP Abstract Classes PHP Interfaces PHP Traits PHP Static Methods PHP Static Properties PHP Namespaces PHP Iterables PHP Advanced PHP Date and Time PHP Include PHP File Handling PHP File Open/Read PHP File Create/Write PHP File Upload PHP Cookies PHP Sessions PHP Filters PHP Filters Advanced PHP Callback Functions PHP JSON PHP Exceptions PHP Forms PHP Form Handling PHP Form Validation PHP Form Required PHP Form URL/E-mail PHP Form Complete

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