What potential issues can arise when sorting data in a PHP query by multiple columns, such as 'date' and 'attached'?

When sorting data in a PHP query by multiple columns, such as 'date' and 'attached', potential issues can arise if the data types are not compatible or if the columns have NULL values. To solve this, you can use the COALESCE function to handle NULL values and ensure that the data types match for proper sorting. 

$query = "SELECT * FROM table_name ORDER BY COALESCE(date_column, '9999-12-31') ASC, COALESCE(attached_column, '') ASC";
$result = mysqli_query($connection, $query);

if(mysqli_num_rows($result) > 0) {
    while($row = mysqli_fetch_assoc($result)) {
        // Process the sorted data
    }
}

Keywords

PHP sorting multiple columns data query

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