Dynamic Pivot table columns mysql

Question

I have following tables

demographic_categories

demographic_id  demographic_name
1               color
2               age_group
<         


        

Answer 1

Your dynamic SQL is just fine except for one thing. It has an ambiguous column project_id on your second left join, Just replace it with pt.project_id or trd.project_id and it will give desired result.

SET @sql = NULL;
    SELECT
      GROUP_CONCAT(DISTINCT
        CONCAT(
          'max(case when dc.demographic_name = ''',
          demographic_name,
          ''' then trd.demographic_value end) AS ',
          replace(demographic_name, ' ', '')
        )
      ) INTO @sql
    from demographic_categories;

SET @sql = CONCAT('SELECT pt.test_id, pt.group_id,
', @sql,'
from test_demographic_requirements trd
LEFT JOIN demographic_categories dc ON trd.demographic_id = dc.demographic_id
LEFT JOIN project_tests pt ON pt.test_id = trd.test_id and pt.project_id =1
group by pt.test_id;');

PREPARE stmt FROM @sql;
EXECUTE stmt;

DEALLOCATE PREPARE stmt;

I ran it on a rextester. Here is the link : dynamic_pivot_test