Question

I have these three tables,

page table

page_id    page_title
1          a

content table

content_id   content_text
1            text one
2            text two

content structure table

page_id     content_id     order_in_page
1           1              1
1           2              2

my working sql,

SELECT 
    p.*,
    c.*,
    x.*

FROM pages AS p

LEFT JOIN pages_structures AS x
ON x.page_id = p.page_id

LEFT JOIN  pages_contents AS c
ON c.content_id = x.content_id

WHERE p.page_url = 'a'

result,

page_id   page_title   content_text    order_in_page
1         a            text one        1    
1         a            text two        2

the result I am after

page_id   page_title   content_1   content_2    content_3    content_4
1         a            text one    text two     null         null

How can I make the multi-row result into a single row result?

Or maybe the multi rows result is better and faster than a single row result that I want?

EDIT:

the reason I want a single row result is that I can just call the content_# by doing this,

echo $page['content_1'];

just like I call the title,

echo $page['page_title'];

Answer 1

You can do this quite easily using GROUP BY with an IF statement for each column you want to transpose. When MAX evaluates it will always evaluate a non-null value as greater than NULL.

SELECT
   page_id,
   page_title, 
   MAX(IF(order_in_page = 1, content_text, NULL)) AS content_1,
   MAX(IF(order_in_page = 2, content_text, NULL)) AS content_2,
   .
   .
   .
FROM 
   pages AS p LEFT JOIN 
   pages_structures AS x ON x.page_id = p.page_id LEFT JOIN  
   pages_contents AS c ON c.content_id = x.content_id
WHERE
   p.page_url = 'a'
GROUP BY page_id