基于两表内联及WHERE条件更新wp_fcfebce_postmeta表meta_value列

Based on your existing SELECT query that links wp_fcfebce_posts and wp_fcfebce_postmeta, here's how you can craft the UPDATE statement to modify the meta_value column for matching records.

Basic Update Syntax (Direct Value Assignment) #

We'll use a JOIN in the UPDATE statement to keep your original filtering logic intact—this is cleaner and more efficient than subqueries for most cases:

UPDATE wp_fcfebce_postmeta pm
JOIN wp_fcfebce_posts p ON pm.post_id = p.ID
SET pm.meta_value = 'your_desired_new_value' -- Replace this with your target value
WHERE p.post_date_gmt > '2018-05-20 00:00:00'
  AND p.post_date_gmt < '2018-05-20 23:59:59'
  AND pm.meta_key = '_wp_attached_file';

Example: Modify Part of the Existing meta_value #

If you need to update a segment of the existing value (like replacing a file path), use MySQL's REPLACE() function:

UPDATE wp_fcfebce_postmeta pm
JOIN wp_fcfebce_posts p ON pm.post_id = p.ID
SET pm.meta_value = REPLACE(pm.meta_value, 'old_path_string', 'new_path_string')
WHERE p.post_date_gmt > '2018-05-20 00:00:00'
  AND p.post_date_gmt < '2018-05-20 23:59:59'
  AND pm.meta_key = '_wp_attached_file';

Critical Tips Before Executing #

• Test first: Run your original SELECT query to confirm exactly which records will be updated. This prevents accidental changes to unintended rows.
• Backup data: For production databases, take a backup of the wp_fcfebce_postmeta table before running any updates.
• Alias clarity: I used aliases (pm for postmeta, p for posts) to simplify the query—feel free to adjust these if you prefer different naming.

内容的提问来源于stack exchange，提问作者Kenh Tre