SELECT
    c.complaint_id,
    GROUP_CONCAT (DISTINCT  file_path SEPARATOR '+ ' )
    from svk_apt_complaints c
     LEFT join svk_apt_master_complaints mc on mc.complaint_type_id = c.complaint_type_id and mc.is_active = 1
     LEFT join svk_apt_complaints_docs cd on cd.complaint_id = c.complaint_id  order by  c.complaint_id