_edit_attachments_query_helper does not properly preface table name when querying unattached media

[benbalter]

If a plugin modifies the media list on upload.php by joining wp_posts on itself (for example, to filter attachments which are children of a certain post type), MySQL throws an error when querying for unattached files because post_parent < 1 in _edit_attachments_query_helper is ambiguous without prefacing the table name (because of the join). All other columns in the query are explicitly named.

Steps to Reproduce:

1. Hook into posts_join_paged on upload.php and join wp_posts on itself ( e.g., JOIN wp_posts wp_posts2 ON wp_posts2.post_parent = wp_posts.ID)
2. Navigate to media upload and query for unattached media
3. Receive an error that post_parent is ambiguous

[benbalter]

Preface table name

[benbalter]

Example join filter to break upload.php (excluded media attached to pages)

[benbalter]

Slightly cleaner, wrapped the string in double quotes

[scribu]

Can't see any downsides to this.

[nacin]

In [19720]:

Prefix table name against the post_parent field in _edit_attachments_query_helper() to avoid ambiguous queries. props benbalter. fixes #19779.