Question

我创建了这个选择查询来获取一些行...它正在工作。但我的问题是我需要从查询中删除重复的行...

这是我的疑问：

SELECT tcs.tutor_id, tcs.category_id, tcs.subject_id, s.subjects, t.tutor_name, t.tutor_code
FROM tutor_category_subject as tcs
INNER JOIN subject AS s ON tcs.subject_id = s.subject_id
INNER JOIN tutors AS t ON tcs.tutor_id = t.tutor_id
WHERE s.subjects LIKE '%business%';

这是它的输出：

    +----------+-------------+------------+------------------+-------------------+-----------+ 

| tutor_id | category_id | subject_id | subjects         | tutor_name        | tutor_code|

+----------+-------------+------------+------------------+-------------------+-----------+

|        1 |           6 |         37 | Business Studies | Tharanga Nuwan    |      1250 |
|        3 |           6 |         37 | Business Studies | Kumara            |      1252 | 
|       15 |           4 |         11 | Business & Accou | Tharanga Nuwan    |      1264 | 
|       15 |           6 |         37 | Business Studies | Tharanga Nuwan    |      1264 |
|       16 |           5 |         11 | Business & Accou | Kasun Kalhara     |      1265 | 
|       16 |           6 |         37 | Business Studies | Kasun Kalhara     |      1265 |

在这里，您可以看到导师ID在我的查询中重复。我需要选择所有科目到一行中以逗号分隔的导师。

例如:(商业与会计研究，商业研究）就像这样..

所以有人能告诉我在我的选择查询中需要做什么吗？

谢谢。

这是我期待的结果

+----------+-------------+------------+-------------------------------------------------+-----------------------+------------+
| tutor_id | category_id | subject_id | subjects                                        | tutor_name            | tutor_code |
+----------+-------------+------------+-------------------------------------------------+-----------------------+------------+
|       16 |           5 |         11 | Business & Accounting Studies, Business Studies | Kasun Kalhara         |       1265 |
|        3 |           6 |         37 | Business Studies                                | Kumara                |       1252 |
|        1 |           6 |         37 | Business Studies, Business & Accounting Studies | Tharanga Nuwan Kumara |       1250 |
+----------+-------------+------------+-------------------------------------------------+-----------------------+------------+

Answer 1

为了让主题在一行中，您应该创建一个函数，该函数将返回逗号分隔的字符串，其中包含每个教师的主题。可能你需要传递一个参数tutor_id（也可能是一个带有你需要添加的“like子句”的字符串）。然后在你的选择中你会有这样的东西：

SELECT tcs.tutor_id, tcs.category_id, t.tutor_name, t.tutor_code, function_name(tcs.tutor_id)
FROM tutor_category_subject as tcs
INNER JOIN tutors AS t ON tcs.tutor_id = t.tutor_id;

Answer 2

尝试：

SELECT DISTINCT tcs.tutor_id, tcs.category_id, tcs.subject_id, s.subjects, t.tutor_name, t.tutor_code
FROM tutor_category_subject as tcs
INNER JOIN subject AS s ON tcs.subject_id = s.subject_id
INNER JOIN tutors AS t ON tcs.tutor_id = t.tutor_id
WHERE s.subjects LIKE '%business%';

或：

SELECT DISTINCTROW tcs.tutor_id, tcs.category_id, tcs.subject_id, s.subjects, t.tutor_name, t.tutor_code
    FROM tutor_category_subject as tcs
    INNER JOIN subject AS s ON tcs.subject_id = s.subject_id
    INNER JOIN tutors AS t ON tcs.tutor_id = t.tutor_id
    WHERE s.subjects LIKE '%business%';

Answer 3

SELECT tcs.tutor_id, tcs.category_id, tcs.subject_id, GROUP_CONCAT(s.subjects) AS subjects,  t.tutor_name, t.tutor_code
FROM tutor_category_subject as tcs
INNER JOIN subject AS s ON tcs.subject_id = s.subject_id
INNER JOIN tutors AS t ON tcs.tutor_id = t.tutor_id
WHERE s.subjects LIKE '%business%'
GROUP BY t.tutor_name;

Answer 4

立即尝试，与group by：

分开

SELECT DISTINCT tcs.tutor_id, tcs.category_id, tcs.subject_id, group_by(s.subjects), t.tutor_name, t.tutor_code
    FROM tutor_category_subject as tcs
    INNER JOIN subject AS s ON tcs.subject_id = s.subject_id
    INNER JOIN tutors AS t ON tcs.tutor_id = t.tutor_id
    WHERE s.subjects LIKE '%business%'
    GROUP BY tcs.tutor_id;

我的选择查询删除重复的行

4 个答案: