Mysql / PHP / Smarty - 如何在一行中检索2组不同的行？

Question

I've tried many different ways and searched through other questions and forums, I just can't find what I'm looking for (may be searching for wrong keywords).

Anyways, here's my structure:

mycars 
--car_id (pk)
--make
--model
mycars_details
--car_id (pk)
--option1
--option2
mycars_gallery
--car_id (pk)
--imgcount
--imglink
--imgthumb

I need to pull all 3 tables, which works fine for mycars and mycars_details (there is only 1 row per PK), but my mycars_gallery has 3 rows(images) for 1 car. User can upload up to 12 images for 1 car.

So when I run this sql:

SELECT * FROM mycars c 
LEFT OUTER JOIN mycars_gallery g 
ON c.car_id = g.car_id 
LEFT OUTER JOIN mycars_details d 
ON c.car_id = d.car_id 
WHERE c.status = 1 AND c.car_id = 27

Output:

|car_id|make|model|option1|option2|imgcount|imglink  |imgthumb   |
  --------------------------------------------------------------
|  27  |volk|jetta|   1   |   0   |   1    |link1.jpg|thumb1.jpeg|
|  27  |volk|jetta|   1   |   0   |   2    |link2.jpg|thumb2.jpeg|
|  27  |volk|jetta|   1   |   0   |   3    |link3.jpg|thumb3.jpeg|

So i get all these duplicates from other tables. This data I store in smarty array and I spit it out on the page using smarty loop.

Something like this:

{section name=car loop=$SHOW_ARRAY}
    {$SHOW_ARRAY[car].make} - {$SHOW_ARRAY[car].model}<br>

    {$SHOW_ARRAY[car].imglink}
{/section}

Question: I feel like my query is wrong, how can I retrieve a single car with all of the images stored in database (mycars_gallery tbl)

Answer 1

Try following query:

SELECT c.car_id,c.make,c.model, d.option1, d.option2,
MAX(CASE WHEN G.IMGTHUMB = 'thumb1.jpg' THEN G.IMGTHUMB ELSE 0 END) AS T1,
MAX(CASE WHEN G.IMGTHUMB = 'thumb2.jpg' THEN G.IMGTHUMB ELSE 0 END) AS T2,
MAX(CASE WHEN G.IMGTHUMB = 'thumb3.jpg' THEN G.IMGTHUMB ELSE 0 END) AS T3
FROM mycars c 
Inner JOIN mycars_gallery g 
ON c.car_id = g.car_id 
Inner JOIN mycars_details d 
ON c.car_id = d.car_id 
WHERE c.car_id = 27;

See Demo at: http://sqlfiddle.com/#!2/3e90b/13

Also an possible alternative is the use of group_concat() function in mysql.

I am assuming that you are working on MySQL, Please use the following generalized query to achieve the same.

SET @sql = NULL;
SELECT 
  GROUP_CONCAT(DISTINCT
    CONCAT(
      'max(case when g.imgthumb = ''',
      G.IMGTHUMB,
      ''' then g.imgthumb else 0 end) AS `',
      IMGTHUMB, '`'
    )
  ) INTO @sql
FROM  mycars c 
Inner JOIN mycars_gallery g 
ON c.car_id = g.car_id 
Inner JOIN mycars_details d 
ON c.car_id = d.car_id 
WHERE c.car_id = 27;

SET @sql = CONCAT('select c.car_id,c.make,c.model, d.option1, d.option2, ', @sql, ' 
                  from mycars c 
                  Inner JOIN mycars_gallery g 
                  ON c.car_id = g.car_id 
                  Inner JOIN mycars_details d 
                  ON c.car_id = d.car_id 
                  WHERE c.car_id = 27');

PREPARE stmt FROM @sql;
EXECUTE stmt;
DEALLOCATE PREPARE stmt;

You should be able to run as many images available in your data set. A working fiddle can be found at: http://sqlfiddle.com/#!2/449638/25

Answer 2

What Saurabh included in his comments about possibly using the group concat function would look like this:

SELECT c.*, 
  GROUP_CONCAT(g.imglink) AS links,
  GROUP_CONCAT(g.imgthumb) AS thumbs
FROM mycars c 
LEFT OUTER JOIN mycars_gallery g 
ON c.car_id = g.car_id 
LEFT OUTER JOIN mycars_details d 
ON c.car_id = d.car_id 
WHERE c.status = 1 AND c.car_id = 27
GROUP BY c.car_id;

This would give you the list of thumbs and links as single comma separated values.