What is database in php
With PHP, you can connect to and manipulate databases. Show MySQL is the most popular database system used with PHP. What is MySQL?
The data in a MySQL database are stored in tables. A table is a collection of related data, and it consists of columns and rows. Databases are useful for storing information categorically. A company may have a database with the following tables:
PHP + MySQL Database System
Database QueriesA query is a question or a request. We can query a database for specific information and have a recordset returned. Look at the following query (using standard SQL): SELECT LastName FROM Employees The query above selects all the data in the "LastName" column from the "Employees" table. To learn more about SQL, please visit our SQL tutorial. Download MySQL DatabaseIf you don't have a PHP server with a MySQL Database, you can download it for free here: http://www.mysql.com Facts About MySQL DatabaseMySQL is the de-facto standard database system for web sites with HUGE volumes of both data and end-users (like Facebook, Twitter, and Wikipedia). Another great thing about MySQL is that it can be scaled down to support embedded database applications. Look at http://www.mysql.com/customers/ for an overview of companies using MySQL. What is MySQL?
Downloading MySQL Database How to connect PHP with MySQL Database?
Difference Between MySQLi and PDO
There are three ways of working with MySQl and PHP
Connecting to MySQL database using PHP
// Creating connection $conn = new mysqli($servername, $username, $password); // Checking connection if ($conn->connect_error) { die("Connection failed: " . $conn->connect_error); } echo "Connected successfully"; ?> Output: Explanation: We can
create an instance of the mysqli class providing all the necessary details required to establish the connection such as host, username, password etc. If the instance is created successfully then the connection is successful otherwise there is some error in establishing connection.
// Creating connection $conn = mysqli_connect($servername, $username, $password); // Checking connection if (!$conn) { die("Connection failed: " . mysqli_connect_error()); } echo "Connected successfully"; ?> Output: Explanation: In MySQLi procedural approach instead of creating an instance we can use the mysqli_connect() function available in PHP to establish a connection. This function takes the information as arguments such as host, username , password , database name etc. This function returns MySQL link identifier on successful connection or FALSE when failed to establish a connection.
// setting the PDO error mode to exception $conn->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION); echo "Connected successfully"; } catch(PDOException $e) { echo "Connection failed: " . $e->getMessage(); } ?> Output: Explanation:The exception class in PDO is used to handle any problems that may occur in our database queries. If an exception is thrown within the try{ } block, the script stops executing and flows directly to the first catch(){ } block. Closing A Connection When we establish a connection to MySQL database from a PHP script , we should also disconnect or close the connection when our work is finished. Here we have described the syntax of closing the connection to a MySQL database in all 3 methods described above. We have assumed that the reference to the connection is stored in $conn variable.
$conn->close();
mysqli_close($conn);
$conn = null; What is the use of database in PHP?The data in a MySQL database are stored in tables. A table is a collection of related data, and it consists of columns and rows. Databases are useful for storing information categorically.
Where is database PHP?The database configuration file is app/config/database. php . In this file you may define all of your database connections, as well as specify which connection should be used by default.
How many databases are there in PHP?PHP has support for over 20 databases, including the most popular commercial and open source varieties. Relational database systems such as MySQL, PostgreSQL, and Oracle are the backbone of most modern dynamic web sites.
What is PHP SQL?PHP is the most popular scripting language for web development. It is free, open source and server-side (the code is executed on the server). MySQL is a Relational Database Management System (RDBMS) that uses Structured Query Language (SQL). It is also free and open source.
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