Question

So I’ve got a query selecting data from 4 tables:

• cases
• taxonomies (containing titles and data about taxonomies)
• taxonomy_values (possible values for the taxonomies)
• post_taxonomy_values (holds IDs from the case table, and IDs from the taxonomy table to link the two)

I’m attempting to select a row from the cases table and then get all taxonomy names and their values. Here’s what I’ve got so far:

select 
cases.title, cases.content, cases.status, taxonomies.title as 'taxonomy', taxonomy_values.value as 'taxonomy_value'

from cases, post_taxonomy_values, taxonomies, taxonomy_values 

where 
cases.slug = 'b-v-dpp' and
post_taxonomy_values.post = cases.id and
taxonomies.id = post_taxonomy_values.taxonomy and
taxonomy_values.id = post_taxonomy_values.value

But this is what that generates:

So basically what I’d like is to take the taxonomy names and make them column names, and set their values as part of the returned row.

Here’s the structure of the tables:

cases:

taxonomies:

taxonomy_values (‘taxonomy’ references an ID in the taxonomies table):

post_taxonomy_values (‘taxonomy’ references an ID in the taxonomies table and ‘value’ references an ID in the taxonomy_values table):

I’ve written and re-written this query but I just can’t get my head round the problem, any help would be much appreciated!

Answer 1

this should do the trick

select 
cases.title, cases.content, cases.status, 
max(case when post_taxonomy_values.post = cases.id and taxonomies.title = 'Tags' then taxonomies.title else '' end) as Tags,
max(case when post_taxonomy_values.post = cases.id and taxonomies.title = 'Tags' then taxonomy_values.value.value else '' end) as Tags_value,
max(case when post_taxonomy_values.post = cases.id and taxonomies.title = 'Court' then taxonomies.title else '' end) as Court,
max(case when post_taxonomy_values.post = cases.id and taxonomies.title = 'Court' then taxonomy_values.value.value else '' end) as Court_value,
.
.
.

from cases, post_taxonomy_values, taxonomies, taxonomy_values 
where 
cases.slug = 'b-v-dpp' and
taxonomies.id = post_taxonomy_values.taxonomy and
taxonomy_values.id = post_taxonomy_values.value
group by cases.title, cases.content, cases.status