What are some potential pitfalls when trying to get the last date from multiple tables in PHP?

When trying to get the last date from multiple tables in PHP, a potential pitfall is not accounting for the different table structures and column names. To solve this, you can use a UNION query to combine the results from multiple tables and then order the results by date in descending order to get the last date. 

<?php
// Assuming $conn is your database connection

$sql = "(SELECT MAX(date_column) AS last_date FROM table1)
        UNION
        (SELECT MAX(date_column) AS last_date FROM table2)
        UNION
        (SELECT MAX(date_column) AS last_date FROM table3)
        ORDER BY last_date DESC
        LIMIT 1";

$result = $conn->query($sql);

if ($result->num_rows > 0) {
    $row = $result->fetch_assoc();
    $last_date = $row['last_date'];
    echo "The last date from multiple tables is: " . $last_date;
} else {
    echo "No results found";
}

$conn->close();
?>

Keywords

SQL JOIN MAX GROUP BY DATE_FORMAT

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