Suppose I have table name "POST" which only contain "POST_ID" , I have a another table name post_meta , which also contain "POST_ID"(as foreign key) and two other column "meta_key" and "meta_value"
The structure of my tables are
post_ID
1
2
meta_id post_id meta_key meta_value
1 1 suite_size 1000
2 1 suite_number 10
3 2 suite_size 2000
4 2 suite_number 20
I want to create a such table like
post_id suite_size suite_number
1 1000 10
2 2000 20
How can I do this ?
Try this:
SELECT pm.post_ID,
SUM(CASE WHEN pm.meta_key = 'suite_size' THEN pm.meta_value ELSE 0 END) as suite_size,
SUM(CASE WHEN pm.meta_key = 'suite_number' THEN pm.meta_value ELSE 0 END) as suite_number
FROM post_meta pm
GROUP BY pm.post_ID;
OR
If you want all posts whether they are not exists in post_meta table then use below query
SELECT p.post_ID,
SUM(CASE WHEN pm.meta_key = 'suite_size' THEN pm.meta_value ELSE 0 END) as suite_size,
SUM(CASE WHEN pm.meta_key = 'suite_number' THEN pm.meta_value ELSE 0 END) as suite_number
FROM post p
LEFT JOIN post_meta pm ON p.post_id = pm.post_ID
GROUP BY p.post_ID;
You need to use the pivot technique to show row as column to achieve this
select
p.post_ID,
max(case when pm.meta_key = 'suite_size' then pm.meta_value end) as `suite_size`,
max(case when pm.meta_key = 'suite_number' then pm.meta_value end) as `suite_number`
from post p
join post_meta pm on pm.post_id = p.post_ID
group by p.post_ID
The technical post webpages of this site follow the CC BY-SA 4.0 protocol. If you need to reprint, please indicate the site URL or the original address.Any question please contact:yoyou2525@163.com.