Kindly explain database connection (dbconnection.php) page

Question
<?php
if(!isset($_SESSION)) { session_start(); }
error_reporting(E_ALL & ~E_NOTICE  &  ~E_STRICT  &  ~E_WARNING);
$con=mysqli_connect("localhost","root","","agribuzzpro");
echo mysqli_connect_error();
?>
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2023-01-14T06:06:42+05:30 1 Answer 40 views

Answer ( 1 )

  1. StudentProjects.Live
    2023-01-14T06:11:53+05:30
    Reply

    if(!isset($_SESSION)) { session_start(); }

    The code if(!isset($_SESSION)) { session_start(); } is a PHP code that is used to check if a session has been started and if not, it starts a new session.

    $_SESSION is a built-in PHP variable that stores session data. The isset() function is used to check if a variable is set and has a value, in this case it’s checking if the $_SESSION variable has been set.

    The ! before isset() is the negation operator, and it reverses the meaning of the function, so the if statement checks if the variable is not set.

    session_start() is a built-in PHP function that is used to start a new session or resume an existing one. When this function is called, it checks if a session has been started, if not, it creates a new session and generates a session ID which is sent to the browser in the form of a cookie.

    So, this code checks if a session has not been started, and if it hasn’t it will start a new session. This is useful for example when you have multiple pages that need to access session data, it ensures that the session is started before any data is added to it.

    It is important to keep in mind that session_start() must be called before any output is sent to the browser, otherwise, it will cause an error.

    error_reporting(E_ALL & ~E_NOTICE & ~E_STRICT & ~E_WARNING);

    The code error_reporting(E_ALL & ~E_NOTICE & ~E_STRICT & ~E_WARNING); is a PHP code that is used to configure the error reporting settings for a PHP script.

    error_reporting() is a built-in PHP function that sets the error reporting level for a PHP script. The parameter passed to the function is an integer that represents the error reporting level.

    The E_ALL constant is a predefined constant in PHP that represents all error levels. The & symbol is a bitwise operator that is used to perform a bitwise AND operation on the integers.

    The ~ operator is the bitwise NOT operator, it inverts the bits of the integer. And the & operator is used to perform a bitwise AND operation on the integers.

    The ~E_NOTICE and ~E_STRICT and ~E_WARNING are used to exclude specific error levels from the error reporting level.

    So, in this case, this code is setting the error reporting level to all error levels except for E_NOTICE, E_STRICT and E_WARNING. This is useful for suppressing certain types of notices, warnings, and strict standards that don’t affect the functionality of the script.

    It is important to note that this setting affects only the current script and it’s not a permanent setting, so it should be used carefully and only when necessary.

    $con=mysqli_connect(“localhost”,”root”,””,”agribuzzpro”);

    The code $con=mysqli_connect("localhost","root","","agribuzzpro"); is a PHP code that is used to establish a connection to a MySQL database.

    mysqli_connect() is a built-in PHP function that is used to connect to a MySQL server. It takes four parameters:

    1. The first parameter is the server address, in this case, it’s “localhost” which means the MySQL server is running on the same machine as the PHP script.

    2. The second parameter is the username, in this case, it’s “root” which is the default username for a local MySQL server installation.

    3. The third parameter is the password, in this case, it’s an empty string, which means no password is set.

    4. The fourth parameter is the name of the database, in this case, it’s “agribuzzpro” which is the name of the database to which the connection should be established.

    The function returns a connection object that can be used to interact with the database, in this case, the connection object is stored in the variable $con.

    This code creates a connection to a MySQL database named ‘agribuzzpro’ running on the localhost using the ‘root’ username and an empty password.

    It’s important to keep in mind that you should not use the root user for production purpose, you should use a different user with specific permissions, and also make sure to not to store the password in clear text in your code.

    echo mysqli_connect_error();

    The code echo mysqli_connect_error(); is a PHP code that is used to display an error message if there is an error while trying to establish a connection to a MySQL database using the mysqli_connect() function.

    mysqli_connect_error() is a built-in PHP function that returns the error message associated with the last call to mysqli_connect(). It takes no parameters.

    The echo statement is used to print the error message to the browser.

    This code can be used after the mysqli_connect() function to check if the connection was successful or not. If the connection was not successful, this line of code will print the error message to the browser, which can be helpful for debugging purposes.

    It’s important to keep in mind that, it’s good practice to display the error message in a development environment, but in a production environment, it’s better to log the error message rather than display it to the end user, because it could reveal sensitive information that could be used by an attacker.

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