Tricky WP Query

For that kind of complex query, I’d recommend running two queries and then merging the results.

First, get an array for:

get all posts WHERE ( post_type=”post” AND category = 7 )

Then, get an array for:

( post_type=”case-studies” AND meta_key = ‘homeslide’ AND meta_value = 1 )

Then use array_merge() to combine the arrays and and you have a collection that satisfies your requirements. Yes, you’re doing to queries … but this seems like a fairly quick/easy short-term solution.