Fatal error: Uncaught mysqli_sql_exception: Unknown column 'b.username' in 'field list' in C:\xampp\htdocs\approvall\detail_pengajuan.php:26 Stack trace: #0 C:\xampp\htdocs\approvall\detail_pengajuan.php(26): mysqli_query(Object(mysqli), 'SELECT a.id_pen...') #1 {main} thrown in C:\xampp\htdocs\approvall\detail_pengajuan.php on line 26