How to query mysql database from php?

@lizzie 

To query a MySQL database from PHP, you can follow these steps:

1. Connect to the MySQL database: Use the mysqli_connect() function to establish a connection to the MySQL server. It takes four arguments - hostname, username, password, and database name.

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$hostname = 'localhost';
$username = 'root';
$password = 'password';
$database = 'mydb';

$conn = mysqli_connect($hostname, $username, $password, $database);

if (!$conn) {
    die("Connection failed: " . mysqli_connect_error());
}

1. Write the SQL query: Use the SQL language to write the query you want to execute. For example, to select all records from a table named "users":

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$sql = "SELECT * FROM users";

1. Execute the query: Use the mysqli_query($conn, $sql) function to execute the SQL query. It takes the database connection object and the SQL query as arguments.

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$result = mysqli_query($conn, $sql);

if (!$result) {
    die("Query failed: " . mysqli_error($conn));
}

1. Fetch the data: Use the mysqli_fetch_assoc($result) function to retrieve each row of data from the result set. It returns an associative array where the keys are column names.

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while ($row = mysqli_fetch_assoc($result)) {
    // Access data using column names
    echo "Name: " . $row["name"] . ", Email: " . $row["email"] . "<br>";
}

1. Close the connection: Use the mysqli_close($conn) function to close the database connection when you are done.

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mysqli_close($conn);

Make sure to handle any errors or exceptions that may occur during the process. Additionally, it's recommended to use prepared statements to prevent SQL injection attacks.