How can you handle cases where one table may not have a corresponding entry in another table when joining them in PHP?

When joining tables in PHP, you may encounter cases where one table does not have a corresponding entry in another table. To handle this situation, you can use a LEFT JOIN in your SQL query. This will return all records from the left table (the one mentioned first in the query) and the matched records from the right table, with NULL values for columns from the right table where there is no match. 

<?php
// Establish a connection to the database
$pdo = new PDO('mysql:host=localhost;dbname=mydatabase', 'username', 'password');

// SQL query with LEFT JOIN to handle missing entries
$sql = "SELECT t1.column1, t2.column2 
        FROM table1 t1 
        LEFT JOIN table2 t2 ON t1.id = t2.id";

// Execute the query
$stmt = $pdo->query($sql);

// Fetch and display the results
while ($row = $stmt->fetch()) {
    echo $row['column1'] . ' - ' . $row['column2'] . '<br>';
}
?>

Keywords

PHP MySQL JOIN LEFT JOIN NULL values

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