Question

Here’s my database structure:

And here’s the SQL statement I’m attempting:

SELECT
 t1.Name AS Teacher_Name,
 t2.Name AS Observer_Name,
 o.Datetime AS Datetime,
 o.Type AS Type,
 o.Year_Group AS Year_Group,
 o.Class_Name AS Class_Name,
 c.Title AS Course_Name,
 GROUP_CONCAT(f.Focus_ID) AS Focus,
 o.Achievement_Grade AS Achievement_Grade,
 o.Behaviour_Grade AS Behaviour_Grade,
 o.Teaching_Grade AS Teaching_Grade,
 o.Notes AS Notes
FROM observations o
INNER JOIN teachers t1 ON o.Teacher_ID = t1.Teacher_ID
INNER JOIN teachers t2 ON o.Observer_ID = t2.Teacher_ID
INNER JOIN courses c ON o.Course_ID = c.Course_ID
INNER JOIN foci f ON f.Observation_ID = o.ID
ORDER BY `Datetime` DESC LIMIT 0,10

What I’m trying to achieve is, within the above statement, to retrieve a list of Foci with a , separator such as Appraisal,Post 16,Teaching and Learning.

This would be achieved by retrieving every row in the Foci table where Foci.Observation_ID meets Observations.ID and then retrieving the name of each focus from Focus_Labels.Title if Foci.Focus_ID matches Focus_Labels.ID.

In the statement above I didn’t get as far as trying to retrieve Focus_Labels.Title because I couldn’t even get the Foci.ID working.

Can anyone help?

Answer 1

I would suggest a slight change from an INNER JOIN to a LEFT JOIN because unless you are certain rows exist in all tables, you will not return results:

SELECT
     t1.Name AS Teacher_Name,
     t2.Name AS Observer_Name,
     o.Datetime AS Datetime,
     o.Type AS Type,
     o.Year_Group AS Year_Group,
     o.Class_Name AS Class_Name,
     c.Title AS Course_Name,
     GROUP_CONCAT(l.title) AS Focus,
     o.Achievement_Grade AS Achievement_Grade,
     o.Behaviour_Grade AS Behaviour_Grade,
     o.Teaching_Grade AS Teaching_Grade,
     o.Notes AS Notes
FROM observations o
LEFT JOIN teachers t1 
    ON o.Teacher_ID = t1.Teacher_ID
LEFT JOIN teachers t2 
    ON o.Observer_ID = t2.Teacher_ID
LEFT JOIN courses c 
    ON o.Course_ID = c.Course_ID
LEFT JOIN  foci f
    ON o.ID = f.Observation_ID
LEFT JOIN focus_labels l
    on f.focus_id = l.id
GROUP BY o.id
ORDER BY `Datetime` 
DESC LIMIT 0,10