清理MySQL查询，Wordpress wp_postmeta

Question

SELECT 
  post_id,meta_key,meta_value 
FROM
  wp_postmeta 
WHERE 
  post_id > 3185 AND
  meta_key = '_shipping_first_name' OR 
  post_id > 3185 AND
  meta_key = '_shipping_last_name' OR
  post_id > 3185 AND
  meta_key = '_shipping_postcode' 
ORDER BY post_id 

post_id meta_key                meta_value
3186    _shipping_first_name    Joe
3186    _shipping_last_name     Svelnys
3186    _shipping_postcode      06040

这是输出数据。我正在尝试将其格式化为

Order  FName  LName    Zip    
3186   Joe    Svelnys  06040

有什么想法吗？我真的很感激。

这是一个帮助的Sqlfiddle http://sqlfiddle.com/#!2/83e232

Answer 1

select wp1.post_id, wp2.meta_value as FName, wp3.meta_value as LName, wp1.meta_value as Zip 
from wp_postmeta wp1 
left join wp_postmeta wp2 
    on wp1.post_id = wp2.post_id 
        and wp2.meta_key = '_shipping_first_name' 
left join wp_postmeta wp3 
    on wp1.post_id = wp3.post_id 
        and wp3.meta_key = '_shipping_last_name' 
where wp1.post_id = 3185 
    and wp1.meta_key = '_shipping_postcode';

这样的东西？

Answer 2

select post_id as OrderNo, 
(select meta_value from wp_postmeta where post_id = w.post_id and meta_key = '_shipping_first_name') as FName,
(select meta_value from wp_postmeta where post_id = w.post_id and meta_key = '_shipping_last_name') as LName,
(select meta_value from wp_postmeta where post_id = w.post_id and meta_key = '_shipping_postcode') as Zip
from wp_postmeta w where w.post_id > 3185 group by post_id

在这里小提琴：http://www.sqlfiddle.com/#!2/b3606/10

Answer 3

标准解决方案看起来像这样，但是类似于J33nn的解决方案版本应该也能正常工作 - 甚至可能更快！

SELECT post_id
     , MAX(CASE WHEN meta_key = '_shipping_first_name' THEN meta_value END) fname
     , MAX(CASE WHEN meta_key = '_shipping_last_name' THEN meta_value END) lname
     , MAX(CASE WHEN meta_key = '_shipping_postcode' THEN meta_value END) zip
  FROM wp_postmeta 
 WHERE post_id > 3185 
 GROUP   
    BY post_id;