This manual describes the PHP extensions and interfaces that can be used with MySQL. For legal Buffered and Unbuffered queries. Presented by developerWorks, your source for great tutorials aracer.mobi MySQL SQL is the standard query language for interacting with databases. MySQL is. Querying a MySQL Database with PHP. The Process .. In the following section, you will gain a grounding in the PHP programming language, covering the.
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Do you want a simple reference on PHP CRUD Tutorial, or how to do CRUD table to display the data retrieved from the MySQL database. 14 results implement SQL database programming into a PHP-based web application. how to search databases and how to incorporate them into PHP-based. The PHP Hypertext Preprocessor (PHP) is a programming language that allows web developers to create dynamic content that interacts with databases. PHP is.
When called, it simply returns the HTML markup to create our form. This is, essentially, a shortcut that references the file you're currently using in our case, it's display.
This is useful if you'll be reusing your code across a site and don't necessarily want to rewrite this function for each page. This is extraordinarily useful for folks like me who take issue with cluttered source code. Saving the Data to the Database Our form will allow us to input information, so how do we save it? That's where our write method comes in.
This process is repeated for our second input, and then both variables are checked to make sure nothing is blank before saving to the database. We now have three variables, and because we've run checks, we know that all three variables are not empty. Now we can write our MySQL query that will save the entry in the database!
Displaying the Information from the Database Now that we have the means to put information into our database, we need to create a way to get that information back out. This is by far the most complex of our methods, so let's really take our time and figure out what's going on inside.
Please check back soon, or click the link below to add an entry! First, we ask the database a question query , to which it replies with a result resource. However, this result isn't really useful until we've decoded it using one of several methods that "fetch," or organize, the information that's contained inside into a usable form array. This is where it gets a bit tricky. Information from the database is returned as an array , which is organized similarly to the database table itself.
To get all of the returned entries, we have to use a while loop. After that, we simply wrap the variables in some HTML and, voila! As a final step, the code adds a link to the bottom that allows users to add an entry.
It's worth noting the use of the ". So, you've now written your first CMS class! You can easily write and retrieve data to and from a database. All that's left to do is to try it out! Using the Class To use our class, we need to create a separate file. I'm going to call it "display. To start, we just set up a document with plain ol' HTML. Then, we have to instantiate our object so that our code knows what's going on.
Page 14 of An array where each ID key is associated with a value Multidimensional array. Instead of having many similar variables. An array containing one or more arrays Numeric Arrays A numeric array stores each element with a numeric ID key. An array with a numeric ID key Associative array. What is an array? When working with PHP. Example 1 In this example we use an array to assign ages to the different persons: Example 2 This example is the same as example 1.
Example 2 In this example we assign the ID key manually: When storing data about specific named values. Page 15 of With associative arrays we can use the values as keys and assign values to them. The ID keys can be used in a script: Peter is 32 years old. Example In this example we create a multidimensional array.
Page 16 of Multidimensional Arrays In a multidimensional array. And each element in the sub-array can be an array. The code above will output: Is Megan a part of the Griffin family? Page 17 of Looping Very often when you write code. You can use looping statements in your code to perform this. Page 18 of Example The following example demonstrates a loop that will continue to run as long as the variable i is less than Syntax while condition code to be executed..
Syntax for init. Is mostly used to set a counter.
Example The following example will increment the value of i at least once. Page 19 of In it's simplest form. If the condition evaluates to TRUE. Is mostly used to increment a counter. Is evaluated at beginning of each loop iteration. All expressions separated by a comma are evaluated but the result is taken from the last part. Example The following example prints the text "Hello World!
This is useful when using a conditional break statement inside the loop for ending the loop. For every loop. Each of the parameters can be empty or have multiple expressions separated by commas. This parameter being empty means the loop should be run indefinitely. Creating PHP functions: It should be possible to understand what the function does by its name.
In PHP. PHP Functions In this tutorial we will show you how to create your own functions. The function is finished by a closing curly brace Example A simple function that writes my name when it is called: For a reference and examples of the built-in functions.
You may have noticed the parentheses after the function name. The parameters are specified inside the parentheses. To add more functionality to a function. Adding parameters Our first function writeMyName is a very simple function. Page 22 of A parameter is just like a variable.
PHP Functions. That's right. Hello world! My name is Kai Jim Refsnes. It only writes a static string. Kai Jim Refsnes is my name. Example 2 The following function has two parameters: My name is Stale Refsnes. My name is Hege Refsnes.
Return values Functions can also be used to return values. My name is Hege Refsnes! Form example: Page 24 of Client side validation is faster. This makes it easier to discover the error. You should always use server side validation if the form accesses a database. When the user fills in this form and click on the submit button.
A good way to validate a form on the server is to post the form to itself. You are 28 years old. The "welcome. Page 25 of Welcome John. The user will then get the error messages on the same page as the form.
Form Validation User input should be validated whenever possible. So this method should not be used when sending passwords or other sensitive information! This can be useful in some cases. Page 26 of Information sent from a form with the GET method is visible to everyone it will be displayed in the browser's address bar and it has limits on the amount of information to send max. Information sent from a form with the POST method is invisible to others and has no limits on the amount of information to send.
Syntax date format. The current month. Here are some of the letters that can be used: Adding a Timestamp Page 29 of The current year in four digits An overview of all the letters that can be used in the format parameter. PHP Date. Specifies a timestamp. It uses letters to represent date and time formats.
What is a Timestamp? A timestamp is the number of seconds since January 1. This is also known as the Unix Timestamp. Other characters.
Specifies the format of the timestamp Optional. Default is the current date and time as a timestamp PHP Date. The include function generates a warning but the script will continue execution while the require function generates a fatal error and the script execution will stop after the error.
Page 30 of In our next example we will use the mktime function to create a timestamp for tomorrow. The mktime function returns the Unix timestamp for a specified date.
Syntax mktime hour. This parameter is optional. The two functions are identical in every way. Reference For more information about all the PHP date functions. These two functions are used to create functions. If you do not supply a timestamp. To include the header file in a page. Here is the code in "default. Example 1 Assume that you have a standard header file.
This means that you can create a standard header or menu file that you want all your web pages to include. The include Function The include function takes all the text in a specified file and copies it into the file that uses the include function. When the header needs to be updated. Look at the "menu.
If you include a file with the include function and an error occurs. By using include files. The require Function The require function is identical to include. PHP code: Page 32 of It is recommended to use the require function instead of include. Failed opening required 'wrongFile. Failed opening 'wrongFile. No such file or directory in C: Notice that the echo statement is still executed! This is because a Warning does not stop the script execution.
The first parameter of this function contains the name of the file to be opened and the second parameter specifies in which mode the file should be opened: The file may be opened in one of the following modes: Starts at the beginning of the file Write only. Opens and clears the contents of file; or creates a new file if it doesn't exist Append. Preserves file content by writing to the end of the file Write only.
Creates a new file. If the fopen function is unable to open the specified file, it returns 0 false. Example The following example generates a message if the fopen function is unable to open the specified file: Closing a File The fclose function is used to close an open file: The feof function is useful for looping through data of unknown length. You cannot read from files opened in w, a, and x mode! Reading a File Line by Line The fgets function is used to read a single line from a file.
After a call to this function the file pointer has moved to the next line. The example below reads a file line by line, until the end of file is reached: Reading a File Character by Character The fgetc function is used to read a single character from a file. After a call to this function the file pointer moves to the next character. The example below reads a file character by character, until the end of file is reached: Only permit trusted users to perform file uploads. Look at the following HTML form for uploading files: For example.
Create an Upload-File Form To allow users to upload files from a form can be very useful. Page 37 of Allowing users to upload files is a big security risk. Page 38 of The first parameter is the form's input name and the second index can be either "name". For security reasons. Restrictions on Upload In this script we add some restrictions to the file upload. Like this: The user may only upload. Saving the Uploaded File The examples above create a temporary copy of the uploaded files in the PHP temp folder on the server.
The temporary copied files disappears when the script ends. Page 39 of For IE to recognize jpg files the type must be pjpeg. To store the uploaded file we need to copy it to a different location: Each time the same computer requests a page with a browser. Page 40 of What is a Cookie? A cookie is often used to identify a user. A cookie is a small file that the server embeds on the user's computer.
With PHP. How to Create a Cookie? The setcookie function is used to set a cookie. Syntax setcookie name. This example saves the file to a new folder called "upload" PHP Cookies A cookie is often used to identify a user. It may be easier than using seconds.. Example 2 You can also set the expiration time of the cookie in another way. We also specify that the cookie should expire after one hour: In the example below.
The value of the cookie is automatically URLencoded when sending the cookie. How to Retrieve a Cookie Value? When deleting a cookie you should assure that the expiration date is in the past.
One method is to pass the data through forms forms and user input are described earlier in this tutorial. The form below passes the user input to "welcome. Delete example: If your application deals with browsers that do not support cookies. A PHP session solves this problem by allowing you to store user information on the server for later use i.
This is much like a Session. The computer knows who you are. If you need a permanent storage you may want to store the data in a database. Session variables hold information about one single user. It knows when you start the application and when you end. But on the internet there is one problem: If "views" has been set. If "views" doesn't exist. The isset function checks if the "views" variable has already been set. Syntax Page 45 of The unset function is used to free the specified session variable: Specifies the subject of the email.
Specifies additional headers. Lines should not exceed 70 characters Optional. Read more in our PHP Mail reference.
This parameter cannot contain any newline characters Required. This is a simple email message. Defines the message to be sent. Specifies an additional parameter to the sendmail program headers parameters Note: For the mail functions to be available. The program to be used is defined by the configuration settings in the php.
PHP requires an installed and working email system. The example below sends a text message to a specified e-mail address: This is the simplest way to send e-mail. Page 47 of In the next chapter of this tutorial you can read more about vulnerabilities in e-mail scripts. When the user clicks the submit button. What happens if the user adds the following text to the email input field in the form?
Page 49 of The code below is the same as in the previous chapter. An error message with filename. Page 50 of Page 51 of This tutorial contains some of the most common error checking methods in PHP. If your code lacks error checking code. We will show different error handling methods: Using the die function The first example shows a simple script that opens a text file: Let's take a look at alternative PHP functions for handling errors.
Page 52 of Must be a value number. This function must be able to handle a minimum of two parameters error level and error message but can accept up to five parameters optionally: Specifies the error report level for the user-defined error.
Specifies the filename in which the error occurred Optional. We simply create a special function that can be called when an error occurs in PHP. Creating a Custom Error Handler Creating a custom error handler is quite simple. Specifies an array containing every variable. The script found something that might be an error. It then outputs the error level and message and terminates the script. Now that we have created an error handling function we need to decide when it should be triggered.
Page 53 of When it is triggered.
We are going to make the function above the default error handler for the duration of the script. Example Page 54 of Example Testing the error handler by trying to output variable that does not exist: It is possible to change the error handler to apply for only some errors.
Since we want our custom function to handle all errors. Possible error types: Value must be 1 or below in C: Non-fatal user-generated run-time warning. Fatal user-generated run-time error. Errors that can not be recovered from. User-generated run-time notice. Send an Error Message by E-Mail In the example below we will send an e-mail with an error message and end the script. PHP sends an error log to the servers logging system or a file. Sending errors messages to yourself by e-mail can be a good way of getting notified of specific errors.
Error Logging By default. Regular errors should be logged on the server using the default PHP logging system. This condition is called an exception.
This is what normally happens when an exception is triggered: Exception handling is used to change the normal flow of the code execution if a specified error exceptional condition occurs. Fatal error: Uncaught exception 'Exception' with message 'Value must be 1 or below' in C: Page 58 of If an exception is not caught.
Exceptions should only be used with error conditions. Basic Use of Exceptions When an exception is thrown. Lets try to throw an exception without catching it: Each "throw" must have at least one "catch" 3. The checkNum function is created. Value must be 1 or below Example explained: The code above throws an exception and catches it: If the exception does not trigger.
This is how you trigger an exception. A function using an exception should be in a "try" block. However if the exception triggers. It checks if a number is greater than 1. A "catch" block retrieves an exception and creates an object containing the exception information Lets try to trigger an exception with valid code: If it is.
The exception within the checkNum function is thrown 4. We simply create a special class with functions that can be called when an exception occurs in PHP. The checkNum function is called in a "try" block 3. Lets create an exception class: The class must be an extension of the exception class.
The custom exception class inherits the properties from PHP's exception class and you can add custom functions to it. Creating a Custom Exception Class Creating a custom exception handler is quite simple. The "try" block is executed and an exception is thrown since the email address is invalid 5. Since it is a copy of the old class. It is possible to use several if. This function returns an error message if an e-mail address is invalid 3.
The errorMessage function is created. The customException class is created as an extension of the old exception class. The "catch" block catches the exception and displays the error message Multiple Exceptions It is possible for a script to use multiple exceptions to check for multiple conditions.
These exceptions can use different exception classes and return different error messages: This way it inherits all methods and properties from the old exception class 2. Example explained: The code above throws an exception and catches it with a custom exception class: Page 61 of The second condition triggers an exception since the e-mail contains the string "example" Page 62 of The "try" block is executed and an exception is not thrown on the first condition 5.
The code above tests two conditions and throws an exception if any of the conditions are not met: System errors may be important for the coder. A script should hide system errors from users. It is possible to throw an exception a second time within a "catch" block. The "catch" block catches the exception and displays the correct error message If there was no customException catch.
To make things easier for the user you can re-throw the exception with a user friendly message: The "catch" block catches the exception and re-throws a "customException" 7. The exception is triggered since the e-mail contains the string "example" 6. Page 64 of The code above tests if the email-address contains the string "example" in it.
The "customException" is caught and displays an error message If the exception is not caught in its current "try" block. The "try" block contains another "try" block to make it possible to rethrow the exception 5. What is a PHP Filter? A PHP filter is used to validate and filter data coming from insecure sources. The PHP filter extension is designed to make data filtering easier and quicker.
Usually this comes from a user or another application like a web service. By using filters you can be sure your application gets the correct input type. If you throw something. To test. Uncaught Exception occurred In the code above there was no "catch" block. This function should be used to catch uncaught exceptions. Page 65 of Why use a Filter? Almost all web applications depend on external input.
If we try with a variable that is not an integer like "abc". Get several input variables and filter them with the same or different filters In the example below. For a complete list of functions and filters. Page 66 of Since the integer is valid. What is external data? Input filtering is one of the most important application security issues.
Different filters have different options and flags. Validating filters: Validate Input Let's try validating input from a form. Since the integer is "" it is not in the specified range. Check if an "email" input variable of the "GET" type exist 2. If the input variable exists. The first thing we need to do is to confirm that the input data we are looking for exists. If a flag is used it does not need to be in an array. Check each filter to see what options and flags are available.
First we confirm that the input data we are looking for exists. The received GET variables is a name. Check if the "url" input of the "POST" type exists 2. Page 70 of If any of the input variables are invalid. Set an array containing the name of input variables and the filters used on the specified input variables 2.
If the parameter is an array it must follow these rules: In an associative array with the name "options" In the example below. This way. Peter is a great guy! Example Explained Page 71 of You can create your own user defined function or use an existing PHP function The function you wish to use to filter is specified the same way as an option is specified. The data in MySQL is stored in database objects called tables. Below is an example of a table called "Persons": Page 72 of A company may have a database with the following tables: A table is a collections of related data entries and it consists of columns and rows.
Each table is identified by a name e. Databases are useful when storing information categorically. What is MySQL? MySQL is a database. Database Tables A database most often contains one or more tables. Queries A query is a question or a request. Tables contain records rows with data. Look at http: Perhaps it is because of this reputation that many people believe that MySQL can only handle small to medium-sized systems.
Look at the following query: The truth is that MySQL is the de-facto standard database for web sites that support huge volumes of both data and end users like Friendster. Page 73 of Specifies the username to log in with. Default value is "localhost: Default value is the name of the user that owns the server process Optional. Parameter Description servername Optional. Default is "" password Note: There are more available parameters.
Specifies the password to log in with. The "die" part will be executed if the connection fails: Specifies the server to connect to. To close the connection before. This function is used to send a query or command to a MySQL connection. Page 75 of Example The following example creates a table named "Persons".. To learn more about SQL. The column names will be "FirstName".. Page 76 of When you create a database field of type varchar. LastName varchar