What is the purpose of using GROUP BY in a MySQL query in PHP?

When using GROUP BY in a MySQL query in PHP, the purpose is to group rows that have the same values in specified columns. This is useful when you want to perform aggregate functions like COUNT, SUM, AVG, etc. on those grouped rows. It helps in organizing and summarizing data based on common attributes. 

<?php
// Connect to database
$servername = "localhost";
$username = "username";
$password = "password";
$dbname = "database";

$conn = new mysqli($servername, $username, $password, $dbname);

// Check connection
if ($conn->connect_error) {
    die("Connection failed: " . $conn->connect_error);
}

// Query with GROUP BY
$sql = "SELECT column1, COUNT(column2) FROM table_name GROUP BY column1";
$result = $conn->query($sql);

// Loop through results
if ($result->num_rows > 0) {
    while($row = $result->fetch_assoc()) {
        echo "Column1: " . $row["column1"]. " - Count: " . $row["COUNT(column2)"]. "<br>";
    }
} else {
    echo "0 results";
}

$conn->close();
?>

Keywords

MySQL GROUP BY PHP query purpose

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