如何從兩個表中獲取數據作爲一行

Question

我有兩個表：

_____________________________ 
| wp_post  | wp_postmeta | 
|______________|_____________| 
| ID   | meta_id  | 
| post_title | post_id  | 
| post_content | meta_key | 
| guid   | meta_value | 
|______________|_____________| 

的wp_postmeta表包含這些行：

| meta_id | post_id | meta_key  | meta_value 
|---------|---------|-----------------|--------------- 
| 310  | 156  | level   | Blue 
| 311  | 156  |_post_main_intro | Some text 

我想要的結果是：

post_title, post_content, meta_value as color, meta_value as main_intro 

我試過不同的連接，但我不能很好地修復它。

SELECT a.post_title, b.meta_key, b.meta_value 
FROM wp_posts a 
LEFT JOIN wp_postmeta b ON a.ID = b.post_id 
WHERE b.meta_key = 'level' 

但是，這並不讓我去取_post_main_intro數據：

我得到這是接近。

我會很高興，如果有人能在正確的方向:)

更新
我目前的解決辦法是這樣的推我（和它的作品）

SELECT a.id, a.post_title, b.meta_value as color, c.meta_value as post_intro 
FROM wp_posts a 
LEFT JOIN wp_postmeta b ON a.ID = b.post_id 
LEFT JOIN wp_postmeta c ON a.ID = c.post_id 
WHERE b.meta_key = 'level' 
AND c.meta_key = '_post_main_intro' 

這是thew去哪裏？

Answer 1

您需要的元表兩次查詢：

SELECT a.post_title, b.meta_key, b.meta_value as level, c.meta_value as intro 
FROM wp_posts a 
LEFT JOIN wp_postmeta b ON a.ID = b.post_id 
LEFT JOIN wp_postmeta c ON a.ID = c.post_id 
WHERE b.meta_key = 'level' 
AND c.meta_key = '_post_main_intro' 

編輯：忘記在這列

Answer 2

嘗試：

 

SELECT a.post_title, b.meta_key, b.meta_value 
FROM wp_posts a 
LEFT JOIN wp_postmeta b ON (a.ID = b.post_id) 
WHERE b.meta_key = 'level' OR b.meta_key = '_post_main_intro' 
 

Answer 3

第三個表，因爲你已經限制搜索到'級別'

WHERE b.meta_key = 'level' 

只要刪除該部分，它應該給你所有