如何从同一列的WordPress自定义字段数据库中检索总和

Question

这是我的查询。 因此，我需要从预算元键的值中检索总和，这些值仅在组件1和2009年。我该怎么做。 提前致谢

SELECT SUM(
b.meta_value)
, b.meta_key
FROM wp_posts AS p, wp_postmeta AS b, wp_postmeta AS m, wp_postmeta AS n
WHERE (
p.ID = b.post_id
)
AND (
b.meta_key =  'budget'
)
AND (
m.meta_key =  'component'
AND m.meta_value =  '1'
)
AND (
n.meta_key =  'component-year'
AND n.meta_value =  '2009'
)

Answer 1

好。 因此，我认为您的意思是您的帖子包含三个自定义字段； “组件”，“组件年份”和“预算”。 当component = 1和component-year = 2009时，您试图获取“预算”的总计值。 如果这是正确的，则可以正常工作-效率不是最高，但是可以正常工作。

SELECT SUM(wp_postmeta.meta_value) AS total
FROM wp_posts 
LEFT JOIN wp_postmeta ON (
    wp_posts.ID = wp_postmeta.post_id
    AND
    wp_postmeta.meta_key = 'budget'
)

# get all the posts with a custom field of "component" of "1"
WHERE wp_posts.ID IN (
    SELECT post_id
    FROM wp_postmeta
    WHERE meta_key =  'component'
    AND meta_value =  '1'
)

# and all the posts with a custom field of "component-year" of "2009"
AND wp_posts.ID IN (
    SELECT post_id
    FROM wp_postmeta
    WHERE meta_key =  'component-year'
    AND meta_value =  '2009'
);