具有多个查找表的 GROUP_CONCAT 和 JOINS

Question

我有一系列简单的GROUP_CONCAT连接，需要在多个表和查找表上执行。

    Table unit:
    +---------+-----------+
    | unit_pk | unit_name |
    +---------+-----------+

    Table unit_outcome:
    +----------------+--------------+
    |unit_outcome_pk | unit_outcome |
    +----------------+--------------+
    
    Table discipline_outcome:
    +----------------------+--------------------+
    |discipline_outcome_pk | discipline_outcome |
    +----------------------+--------------------+
    
    Table unit_outcome_discipline_outcome_lookup:
    +-------------------------------------------+-----------------+-----------------------+
    | unit_outcome_discipline_outcome_lookup_pk | unit_outcome_fk | discipline_outcome_fk |
    +-------------------------------------------+-----------------+-----------------------+

    Table unit_unit_outcome_lookup:
    +----------------------------+-----------------+---------+
    |unit_unit_outcome_lookup_pk | unit_outcome_fk | unit_fk |
    +----------------------------+-----------------+---------+

因此，如果在相应的查找表中unit_fk = 1和unit_fk = 1 discipline_fk = 5 ，则在给定小提琴中的测试数据的情况下，结果应如下所示（下面的链接）：

+---------------+-----------------------+
|unit_outcome 1 | discipline_outcome 10 |
|               |                       |
+---------------+-----------------------+
|unit_outcome 2 | discipline_outcome 7  |
|               |                       |
+---------------+-----------------------+
|unit_outcome 3 | discipline_outcome 1  |
|                 discipline_outcome 8  |
|               | discipline_outcome 9  |
+---------------+-----------------------+

到目前为止，我所拥有的是以下查询， unit_outcome -> discipline_outcomes获取unit_outcome -> discipline_outcomes结果，没有过滤unit和unit_unit_outcome_lookup表，例如unit_fk = '1'以及unit_fk = '1' ：

SELECT unit_outcome, 
GROUP_CONCAT(discipline_outcome SEPARATOR '|') AS discipline_outcomes
FROM unit_outcome u
LEFT JOIN unit_outcome_discipline_outcome_lookup l ON u.unit_outcome_pk = l.unit_outcome_fk
LEFT JOIN discipline_outcome d ON l.discipline_outcome_fk = d.discipline_outcome_pk
WHERE d.discipline_fk = '5' 
GROUP BY unit_outcome

我需要将这两个表合并到上面的查询中，以便只有与给定的 unit_fk 以及 subject_fk 对应的 unit_outcomes。 不知道如何做到这一点。

数据库小提琴

Answer 1

您必须像这样使用 INNER 连接连接所有表：

SELECT u.unit_outcome, 
  GROUP_CONCAT(d.discipline_outcome ORDER BY d.discipline_outcome_pk SEPARATOR '|') AS discipline_outcomes
FROM unit_outcome u
INNER JOIN unit_outcome_discipline_outcome_lookup l ON u.unit_outcome_pk = l.unit_outcome_fk
INNER JOIN discipline_outcome d ON l.discipline_outcome_fk = d.discipline_outcome_pk
INNER JOIN unit_unit_outcome_lookup uu ON uu.unit_outcome_fk = u.unit_outcome_pk
WHERE d.discipline_fk = '5' AND uu.unit_fk = '1'
GROUP BY u.unit_outcome