When should GROUP_CONCAT be used in PHP to concatenate values from a column in a SQL query result set?

When you want to concatenate values from a column in a SQL query result set into a single string, you should use GROUP_CONCAT in PHP. This function is useful when you want to combine multiple values into a comma-separated list. It is commonly used when you have a one-to-many relationship and want to display all related values in a single field. 

// Connect to the database
$pdo = new PDO("mysql:host=localhost;dbname=mydatabase", "username", "password");

// Prepare and execute the SQL query
$stmt = $pdo->prepare("SELECT id, GROUP_CONCAT(value) AS concatenated_values FROM mytable GROUP BY id");
$stmt->execute();

// Fetch the results
while ($row = $stmt->fetch()) {
    echo "ID: " . $row['id'] . ", Concatenated Values: " . $row['concatenated_values'] . "<br>";
}

Keywords

PHP GROUP_CONCAT SQL query result set concatenate

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