将多个列和行合并为一个条目

Question

I have a relational database with one main table linked to other tables with foreign keys. I am trying to write a reporting tool in PHP to grab all the data out but have gotten stck with one part of it.

here is my query so far:

SELECT * 
FROM student s 
LEFT OUTER JOIN ep e ON s.sID = e.sID 
LEFT OUTER JOIN ntc n ON s.sID = n.sID 
LEFT OUTER JOIN pk p ON s.sID = p.sID 
LEFT OUTER JOIN roa r ON s.sID = r.sID 
WHERE s.sID = '$id'

ep, ntc and pk are all 1:1 with student so there are no problems. But the roa table holds multiple records (spanning multiple rows) for each student.

roa table structure:

+----------+--------------+------+-----+-------------------+----------------+
| Field    | Type         | Null | Key | Default           | Extra          |
+----------+--------------+------+-----+-------------------+----------------+
| roaID    | int(11)      | NO   | PRI | NULL              | auto_increment |
| sID      | int(11)      | NO   | MUL | NULL              |                |
| roa      | varchar(255) | NO   |     | NULL              |                |
| roaStaff | varchar(50)  | NO   |     | NULL              |                |
| visible  | tinyint(1)   | NO   |     | 1                 |                |
+----------+--------------+------+-----+-------------------+----------------+

where a select * from roa where sID = 1 returns:

+-------+-----+---------------+----------+---------+
| roaID | sID | roa           | roaStaff | visible |
+-------+-----+---------------+----------+---------+
|    41 | 1   | Description 1 | Staff 1  |       1 |
|    60 | 1   | Description 2 | Staff 2  |       1 |
+-------+-----+---------------+----------+---------+

what I am after my original query to achieve is a result something like:

<-student, etc data
..-------+-----+-----------------------------------------------+---------+
.. roaID | sID | roa                                           | visible |
..-------+-----+-----------------------------------------------+---------+
..    41 | 1   | Description 1 Staff 1, Description 2 Staff 2  |       1 |
...
...

so that both the roa.roa and the roa.roaStaff are all in one cell.

I have tried using GROUP_CONCAT but have only been able to get it to work for one column, not group multiple columns together.

any help is greatly appreciated.

regards.

Answer 1

try something like this,

SELECT ......, GROUP_CONCAT(CONCAT(roa, ' ', roaStaff)) roa
FROM ...

so when you plug it in your query,

SELECT * 
FROM student s 
LEFT OUTER JOIN ep e ON s.sID = e.sID 
LEFT OUTER JOIN ntc n ON s.sID = n.sID 
LEFT OUTER JOIN pk p ON s.sID = p.sID 
LEFT OUTER JOIN 
(
    SELECT sID, GROUP_CONCAT(CONCAT(roa, ' ', roaStaff)) roa
    FROM roa 
    GROUP BY sID
) r ON s.sID = r.sID 
WHERE s.sID = '$id'

follow-up question, how about the visible field on table roa ? How would you want it to be shown

SIDENOTE

your query is vulnerable with SQL INJECTION , please read the article below to learn how to protect from it

• How can I prevent SQL injection in PHP?