Language levels

WordPress database error: [You have an error in your SQL syntax; check the manual that corresponds to your MariaDB server version for the right syntax to use near '' at line 1]
SELECT * FROM `ed_subject` WHERE `id` =

WordPress database error: [You have an error in your SQL syntax; check the manual that corresponds to your MariaDB server version for the right syntax to use near 'and `webpage_visibility` = 1' at line 1]
SELECT `description`, `price`, `level_id`, `id`, `commercial`, `summer`, `paid` FROM `ed_group` WHERE `subject_id` = and `webpage_visibility` = 1

WordPress database error: [You have an error in your SQL syntax; check the manual that corresponds to your MariaDB server version for the right syntax to use near 'and `webpage_visibility` = 1 ) order by `hierarchy`' at line 1]
SELECT * FROM `ed_level` WHERE `id` IN ( SELECT `level_id` FROM `ed_group` where `subject_id` = and `webpage_visibility` = 1 ) order by `hierarchy`