mysql: создать несколько столбцов из одной колонки

Question

Я ищу долгое время для решения этой головоломки, надеюсь, некоторые из вас могут помочь.

У меня есть таблица MySQL, глядя, как это:

**id | role  |** 
-------------------- 
    1 | staff | 
    1 | member | 
    1 | paying | 
    2 | staff | 
    2 | admin | 

У меня есть около 35 различных видов данных в роли. То, что я хочу, это столбец для каждого типа данных в роли, поэтому я получаю что-то вроде этого.

**id | staff | member | paying | admin |** 
------------------------------------------ 
    1 | staff | member | paying | null | 
    2 | staff | null | null | admin | 

Если это поможет я уже удалось сделать строки с помощью CASE, но моя проблема сейчас в том, что я получаю несколько строк с одинаковым идентификатором. И мне нужно объединить их в одну. Пока я пытался использовать группу, но она не работает.

сделать coloumns я использовал этот

create table ahbtest2 as (
    select 
    ahbtest1.*, 
    case when f_name = "newsletter" then f_name end as f_newsletter, 
    case when f_name = "staff" then f_name end as f_staff, 
    case when f_name = "Musician" then f_name end as f_musician, 
    case when f_name = "No_membership" then f_name end as f_no_membership, 
    case when f_name = "Beirut" then f_name end as f_beirut, 
    case when f_name = "VISA" then f_name end as f_visa, 
    case when f_name = "3wc" then f_name end as f_3wc, 
    case when f_name = "Intl_media" then f_name end as f_intl_media, 
    case when f_name = "VIP" then f_name end as f_vip, 
    case when f_name = "Music_industry" then f_name end as f_music_industry, 
    case when f_name = "senegal" then f_name end as f_senegal, 
    case when f_name = "Music_Freedom_Day" then f_name end as f_music_freedom_day, 
    case when f_name = "Scholar/student" then f_name end as f_scholar_student, 
    case when f_name = "Anniversary_booklet" then f_name end as f_anniversary_booklet, 
    case when f_name = "Music_industry" then f_name end as f_music_industry, 
    case when f_name = "Old_membership" then f_name end as f_old_membership, 
    case when f_name = "2wc" then f_name end as f_2wc, 
    case when f_name = "Advisory_Board" then f_name end as f_advisory_board, 
    case when f_name = "Danish_media" then f_name end as f_danish_media, 
    case when f_name = "Business_contacts" then f_name end as f_business_contacts, 
    case when f_name = "Latest_Report" then f_name end as f_latest_report, 
    case when f_name = "Press_Alert" then f_name end as f_press_alert, 
    case when f_name = "Funding/sponsor" then f_name end as f_funding_sponsor, 
    case when f_name = "Diverse/Contacts" then f_name end as f_diverse_contacts, 
    case when f_name = "Honorary_membership" then f_name end as f_honorary_membership, 
    case when f_name = "Supporting_Membership" then f_name end as f_supporting_membership, 
    case when f_name = "GA_2008" then f_name end as f_ga_2008, 
    case when f_name = "Stringer" then f_name end as f_stringer, 
    case when f_name = "Seminar" then f_name end as f_seminar, 
    case when f_name = "Ambassador" then f_name end as f_ambassador, 
    case when f_name = "1wc" then f_name end as f_1wc, 
    case when f_name = "Evaluation Contacts" then f_name end as f_evaluation_contacts, 
    case when f_name = "OIC_APPEAL" then f_name end as f_oic_appeal, 
    case when f_name = "Paying membership" then f_name end as f_paying_membership, 
    case when f_name = "Executive committee" then f_name end as f_executive_committee, 
    case when f_name = "Institutional membership" then f_name end as f_institutional_membership 
    from ahbtest1 

); 

и в попытке объединить строки по идентификатору, это один

select id, name, group_concat(fname) 
    from table 
    group by id, 

Answer 1

Это было бы долго на уровне MySQL, но все же возможно:

select id, staff, member, ccc from roles 
left join (select id, role as staff from roles where role='staff') staff using (id) 
left join (select id, role as member from roles where role='member') member using (id) 
left join (select id, role as paying from roles where role='paying') paying using (id) 
group by id 

Конечно, вы должны расширить этот запрос, чтобы включить все возможные значения.