Error on page <br>1052 - Column 'date_created' in order clause is ambiguous<br>  SELECT 
    distinct( contents.content_id ),
    content_values.main_visible, 
    content_values.title, 
    content_values.content,
    content_values.connection_url,
    content_values.connection_file,
    content_values.connection_type_id,
    connection_types.connection_type,
    content_values.language_id, 
    languages.language,
    contents.department_id, 
    department_values.department,
    parent_departments.department_id as parent_department_id,
    parent_department_values.department as parent_department,
    contents.category_id, 
    category_values.category,
    categories.url,
    contents.menu_id, 
    menu_values.menu,
    menus.parent_menu_id, 
    menu_values.multiple,
    menus.group_id,
    groups.group,
    targets.target,
    targets.target_id,
    content_values.create_user_id, 
    create_users.username as create_username, 
    concat( create_users.lastname, ' ', create_users.firstname ) as create_fullname,
    content_values.update_user_id, 
    update_users.username as update_username, 
    concat( update_users.lastname, ' ', update_users.firstname ) as update_fullname,
    content_values.date_created,
    date_format(content_values.date_created, '%d/%m/%Y' ) as date_created, 
    date_format(content_values.date_updated, '%d/%m/%Y' ) as date_updated, 
    date_format(content_values.date_expired, '%d/%m/%Y' ) as date_expired, 
    date_format(content_values.date_to_view, '%d/%m/%Y' ) as date_to_view, 
    content_values.active,
    content_values.prokiriksi,
    date_format(content_values.hm_sigklisis_simbouliou, '%d/%m/%Y' ) as hm_sigklisis_simbouliou,
    content_values.apospasma_praktikou,
    date_format(content_values.hm_sigklisis_eklektrorikou, '%d/%m/%Y' ) as hm_sigklisis_eklektrorikou,
    content_values.praktiko_orismou_trimelis,
    date_format(content_values.hm_katathesis_isigitikis, '%d/%m/%Y' ) as hm_katathesis_isigitikis,
    date_format(content_values.hm_sigklisis_eklogis, '%d/%m/%Y' ) as hm_sigklisis_eklogis,
    content_values.praktiko_apotelesmatwn
  FROM contents
  LEFT JOIN content_values on content_values.content_id = contents.content_id 
  LEFT JOIN languages on languages.language_id = content_values.language_id
  LEFT JOIN connection_types on connection_types.connection_type_id = content_values.connection_type_id
  LEFT JOIN departments on departments.department_id = contents.department_id
  LEFT JOIN department_values on department_values.department_id = departments.department_id and department_values.language_id = languages.language_id
  LEFT JOIN departments as parent_departments on parent_departments.department_id = departments.parent_id
  LEFT JOIN department_values as parent_department_values on parent_department_values.department_id = parent_departments.department_id and parent_department_values.language_id = languages.language_id
  LEFT JOIN categories on categories.category_id = contents.category_id
  LEFT JOIN category_values on category_values.category_id = contents.category_id and category_values.language_id = languages.language_id
  LEFT JOIN menus on menus.menu_id = contents.menu_id
  LEFT JOIN menu_values on menu_values.menu_id = menus.menu_id and menu_values.language_id = languages.language_id
  LEFT JOIN groups on menus.group_id = groups.group_id
  LEFT JOIN targets on targets.target_id = contents.target_id
  LEFT JOIN users as create_users on create_users.user_id = content_values.create_user_id
  LEFT JOIN users as update_users on update_users.user_id = content_values.update_user_id
WHERE languages.language_id = 1
                AND contents.menu_id = 8025
                AND content_values.active = 1
               UNION   SELECT 
    distinct( contents.content_id ),
    content_values.main_visible, 
    content_values.title, 
    content_values.content,
    content_values.connection_url,
    content_values.connection_file,
    content_values.connection_type_id,
    connection_types.connection_type,
    content_values.language_id, 
    languages.language,
    contents.department_id, 
    department_values.department,
    parent_departments.department_id as parent_department_id,
    parent_department_values.department as parent_department,
    contents.category_id, 
    category_values.category,
    categories.url,
    contents.menu_id, 
    menu_values.menu,
    menus.parent_menu_id, 
    menu_values.multiple,
    menus.group_id,
    groups.group,
    targets.target,
    targets.target_id,
    content_values.create_user_id, 
    create_users.username as create_username, 
    concat( create_users.lastname, ' ', create_users.firstname ) as create_fullname,
    content_values.update_user_id, 
    update_users.username as update_username, 
    concat( update_users.lastname, ' ', update_users.firstname ) as update_fullname,
    content_values.date_created,
    date_format(content_values.date_created, '%d/%m/%Y' ) as date_created, 
    date_format(content_values.date_updated, '%d/%m/%Y' ) as date_updated, 
    date_format(content_values.date_expired, '%d/%m/%Y' ) as date_expired, 
    date_format(content_values.date_to_view, '%d/%m/%Y' ) as date_to_view, 
    content_values.active,
    content_values.prokiriksi,
    date_format(content_values.hm_sigklisis_simbouliou, '%d/%m/%Y' ) as hm_sigklisis_simbouliou,
    content_values.apospasma_praktikou,
    date_format(content_values.hm_sigklisis_eklektrorikou, '%d/%m/%Y' ) as hm_sigklisis_eklektrorikou,
    content_values.praktiko_orismou_trimelis,
    date_format(content_values.hm_katathesis_isigitikis, '%d/%m/%Y' ) as hm_katathesis_isigitikis,
    date_format(content_values.hm_sigklisis_eklogis, '%d/%m/%Y' ) as hm_sigklisis_eklogis,
    content_values.praktiko_apotelesmatwn
  FROM contents
  LEFT JOIN content_values on content_values.content_id = contents.content_id 
  LEFT JOIN languages on languages.language_id = content_values.language_id
  LEFT JOIN connection_types on connection_types.connection_type_id = content_values.connection_type_id
  LEFT JOIN departments on departments.department_id = contents.department_id
  LEFT JOIN department_values on department_values.department_id = departments.department_id and department_values.language_id = languages.language_id
  LEFT JOIN departments as parent_departments on parent_departments.department_id = departments.parent_id
  LEFT JOIN department_values as parent_department_values on parent_department_values.department_id = parent_departments.department_id and parent_department_values.language_id = languages.language_id
  LEFT JOIN categories on categories.category_id = contents.category_id
  LEFT JOIN category_values on category_values.category_id = contents.category_id and category_values.language_id = languages.language_id
  LEFT JOIN menus on menus.menu_id = contents.menu_id
  LEFT JOIN menu_values on menu_values.menu_id = menus.menu_id and menu_values.language_id = languages.language_id
  LEFT JOIN groups on menus.group_id = groups.group_id
  LEFT JOIN targets on targets.target_id = contents.target_id
  LEFT JOIN users as create_users on create_users.user_id = content_values.create_user_id
  LEFT JOIN users as update_users on update_users.user_id = content_values.update_user_id
WHERE languages.language_id = 1
                AND content_values.active = 1
                AND contents.category_id = 9
               ORDER BY BINARY parent_department ASC, department asc, date_created DESC, title ASC