Question

我有6个表，我将做一个单独的sql语句：

1)participant
  ***********
  +id_participant
  +id_poste
  +name
  +email

2) profile_formaion
  ****************
  +id_poste
  +id_formation

3) formation
  *********
  +id_formation
  +lable

4) poste
  *********
  +id_poste
  +label

5) session
  *********
  +id_session
  +id_formaion
  +lable

6) session_composition
  *********
  +id_session
  +id_participant

EXAMPLE:

DATA：参与者

1 | 2 | user1 | user1@mail.com
2 | 3 | user2 | user2@mail.com

DATA：profile_formation

2 | 3
2 | 4

DATA：形成

1 |formation1
2 |formation2
3 |formation3
4 |formation4

DATA：poste

1 |Poste1
2 |Poste2
3 |Poste3

DATA：会话

1 |1   /* id_session 1 to id_formation 1  and id_formation=1 is formation1 */

DATA：session_composition

1 |2  /* id_session 1 to id_participant 2 */

我在尝试：

SELECT 
    participant.id_participant,
    participant.id_poste,
    participant.name,
    participant.email,
    formation.lable 
FROM participant
INNER JOIN profile_formaion ON
    profile_formaion.id_poste = participant.id_poste 
INNER JOIN formation ON
    formation.id_formation = profile_formaion.id_formation

如何使用sql语句（join）获取结果：

DATA：结果

1 | 2 | user1 | user1@mail.com | poste2|formation3
1 | 2 | user1 | user1@mail.com | poste2|formation4
2 | 3 | user2 | user2@mail.com | poste3|formation1 // How can we join to get it.

Answer 1

如果您不反对使用工会，您可以随时执行此操作：

select
    participant.id_participant,
    participant.id_poste,
    participant.name,
    participant.email,
    poste.label,
    formation.lable
from
    participant
    inner join poste on participant.id_poste = poste.id_poste
    inner join profile_formaion on participant.id_poste = profile_formaion.id_poste
    inner join formation on profile_formaion.id_formation = formation.id_formation

union all

select
    participant.id_participant,
    participant.id_poste,
    participant.name,
    participant.email,
    poste.label,
    formation.lable
from
    participant
    inner join poste on participant.id_poste = poste.id_poste
    inner join session_composition on participant.id_participant = session_composition.id_participant
    inner join session on session_composition.id_session = session.id_session
    inner join formation on session.id_formaion = formation.id_formation

使用join构建单个SQL查询。可能吗？

1 个答案: