选择列等于另一个查询的任何值的位置

Question

I have a query to find relationships in a table named entryEntryPairs:

if (!$result = $mysqli->query(
    "SELECT entryIdA AS relatedId FROM entryEntryPairs WHERE entryIdB = ".$inRow["id"].
    " UNION ".
    "SELECT entryIdB AS relatedId FROM entryEntryPairs WHERE entryIdA = ".$inRow["id"]
)) return "Something went wrong";

However, what I really want is to use all of the relatedIds as part of a larger query to a table named entry. Something of the form:

SELECT title FROM entry WHERE id =

The missing section to the right of id = would be all of the relatedIds. Can this be done in a single larger query or do I have to iterate over the results of the first query plugging in each relatedId to the right of id =?

Answer 1

You can try with IN like

"SELECT title FROM entry WHERE id IN (SELECT entryIdA AS relatedId FROM entryEntryPairs WHERE entryIdB = ".$inRow["id"].
" UNION ".
"SELECT entryIdB AS relatedId FROM entryEntryPairs WHERE entryIdA = ".$inRow["id"].")"