將小查詢合併爲一個較大的mysql查詢

Question

我有一個問題，在同一查詢中向不同的表獲取4個SQL請求。查詢是：

SELECT COUNT(*) AS posts FROM `wp_posts` WHERE post_type='updates' AND post_status='publish' 

而且

SELECT COUNT(*) AS posts FROM `wp_posts` WHERE post_type='post' AND post_status='publish' 

的wp_posts表結構是：

| ID | title | post_type | post_status | 
------------------------------------------------ 
| 1 | Name | updates | publish | 
| 2 | Name 2 |  post | publish | 

其他請求：

SELECT COUNT(*) AS users FROM wp_usermeta WHERE wp_usermeta.meta_value LIKE '%delegate%' 

wp_usermeta的表結構我S：

| ID | user_id | meta_key  |   meta_value   | 
----------------------------------------------------------------- 
| 29 | 4 | ei_capabilities | a:1:{s:13:"delegate";b:1;} | 

，最後一個：

SELECT wp_postmeta.meta_value AS version FROM wp_postmeta WHERE wp_postmeta.meta_key='content_version' AND post_id=1 

wp_postmeta表結構是：

| ID | post_id | title | meta_key  | meta_value | 
--------------------------------------------------------------- 
| 21 |  1  | Name | content_version |  1  | 

有沒有辦法將它們組合成一個要求嗎？

Answer 1

首先兩個查詢是相似的，所以我做了wp_posts爲主要table.The其餘兩個查詢的子查詢。

SELECT 
    (SUM(CASE WHEN post_type='updates' AND THEN 1 ELSE 0 END)) as col1, 
    (SUM(CASE WHEN post_type='post' AND post_type='post' THEN 1 ELSE 0 END)) as col2, 
    (SELECT COUNT(*) AS users FROM wp_usermeta WHERE wp_usermeta.meta_value LIKE '%delegate%') AS col3, 
    (SELECT wp_postmeta.meta_value AS version FROM wp_postmeta WHERE wp_postmeta.meta_key='content_version' AND post_id=1 LIMIT 1) as col4 
    FROM 
    wp_posts 
    WHERE post_status='publish' 

希望這有助於

Answer 2

試試這個

select(
    select 
    sum(case when post_type='updates' AND post_status='publish' then 1 else 0 end) from wp_posts) as '1Query', 
    (select 
sum(case when post_type='post' AND post_status='publish' then 1 else 0 end) as '2Query' 
    from wp_posts), 
    (select 
    SUM(CASE WHEN wp_usermeta.meta_value LIKE '%delegate%' THEN 1 ELSE 0 END) AS users 
    FROM wp_usermeta) as Users, 
    (
    SELECT wp_postmeta.meta_value AS version FROM wp_postmeta WHERE wp_postmeta.meta_key='content_version' AND post_id=1)as Version