Dropping a database requires that no Java classes in the database being dropped are referenced by objects in temporary databases. These can exist as a result of select into #temptable commands. In such cases, columns in a temporary table refer back to classes in the source database. All temporary databases are scanned to make sure that no such references exist. If such references exist, the database is not dropped.
This behavior is consistent with the behavior of an Adaptive Server without the multiple temporary database feature.