Heredoc is one of the useful solution to secure better readability when we code SQL Query in PHP
Below is an example using Heredoc for SQL Query in PHP
$sql = <<<SQL select * from class where grade>5 SQL;
Below is another example using Heredoc with variables for SQL Query in PHP
$sql = <<<SQL insert into celebrity( id, name, gender, year, month, day, hour, lunar, img, thumbnail, created_at, updated_at, active) values('{$id}', '{$name}', '{$gender}', {$yy}, {$mm}, {$dd}, {$hh}, '{$lunar}', '{$new_img_filename}', '{$new_thumbnail_filename}', '{$now}', '{$now}', true) SQL;