php query database array

In PHP development, database query is one of the essential operations. As an efficient dynamic language, PHP provides many built-in functions to help us perform database operations. The most important of these are PHP's arrays.

Array is one of the most important and commonly used structures in the PHP language. They can be used to store and manipulate data, or to hold multiple pieces of data in a single variable. Using arrays, we can easily obtain data from the database, analyze and process it.

In this article, we will discuss how to use PHP arrays to query the database.

Connect to the database

Before operating the database, we need to connect to the database first. You can use the PHP built-in function mysqli_connect(). Here is the code to connect to the database using this function:

$host = "localhost";
$user = "root";
$password = "";
$database = "test_db";

$con = mysqli_connect($host, $user, $password, $database);

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

This code will connect to the database named "test_db". If the connection fails, an error message is output and execution of the script is terminated.

Query database

With the connection, we can query the database. You can use the PHP built-in function mysqli_query(). Here is the code to query the database:

$sql = "SELECT * FROM users";
$result = mysqli_query($con, $sql);

if (mysqli_num_rows($result) > 0) {
    while ($row = mysqli_fetch_assoc($result)) {
        $users[] = $row;
    }
} else {
    echo "0 results";
}

mysqli_close($con);

This code will query all rows in the database table named "users". Store the query results in an array named $users.

Parsing results

We can use PHP arrays to parse and process database query results. For example:

foreach ($users as $user) {
    echo "ID: " . $user["id"] . "<br>";
    echo "Name: " . $user["name"] . "<br>";
    echo "Email: " . $user["email"] . "<br><br>";
}

This code will use a foreach loop to iterate through each item in the $users array. For each user, the code will display their ID, name, and email.

You can also use other array functions to process query results. For example, you can use the array_count_values() function to count the number of occurrences of a value for a specific column:

$email_counts = array_count_values(array_column($users, "email"));
print_r($email_counts);

This code will use the array_column() function to extract the "email" column in the $users array and use the array_count_values() function to count each The number of times the email address appears.

Summary

PHP arrays are a powerful tool for manipulating database query results. In PHP development, it is often necessary to perform query operations and use arrays to process and analyze the returned results. You can use various built-in functions and array functions provided by PHP to easily manipulate the database and use arrays for parsing and processing.

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