Question

I have a table with this structure

TABLE #1
---------------------------------------------------------------------------
meta_id | post_id |    meta_key    |               meta_value          |
---------------------------------------------------------------------------
1234         5      thumbnail_url      http://www.domain/thumb.jpg
1235         5      swf_url            http://www.domain/flash.swf
1236         5      description        This is a description.
1237         6      thumbnail_url      http://www.domain/thumb.jpg
1238         6      swf_url            http://www.domain/flash.swf
1239         6      description        This is a description.
---------------------------------------------------------------------------

and another table with this structure

TABLE #2
----------------------------------------------------
ID |   post_title   | thumbnail | swf | description
----------------------------------------------------
5     Awesome Title     NULL     NULL    NULL
6    Stack Over Flow    NULL     NULL    NULL 
----------------------------------------------------

I need to copy and paste over the meta values from Table 1 over to Table 2 WHERE post_id = ID.

Any insights on how the query would look like would be greatly appreciated.

Answer 1

UPDATE Table2 t2
INNER JOIN
(
   SELECT
     post_id, 
     MAX(CASE WHEN meta_key = 'thumbnail_url' THEN meta_value END) AS 'thumbnail', 
     MAX(CASE WHEN meta_key = 'swf_url' THEN meta_value END) AS 'swf',
     MAX(CASE WHEN meta_key = 'description' THEN meta_value END) AS 'description'
   FROM Table1
   GROUP BY post_id
) t1 ON t1.post_id = t2.id
SET t2.thumbnail = t1.thumbnail,
    t2.swf       = t1.swf,
    t2.description = t1.description;

SQL Fiddle Demo