Example of search fields available in OmniFile Full-Text Mega.
Most databases do not actually contain the full text of articles. Instead they have metadata, data about the data. Your search words need to match words used in the metadata to get results. Common metadata fields for articles include:
The basic search typically searches all metadata fields, but there's usually an advanced search screen where you can select specific fields.
Choosing the right search field can be crucial. You'll get very different results searching "Shakespeare" as an author or as a subject.
Even databases that can search full-text often have the option of limiting your search to just the metadata.
When to Use Full-Text Searching
When to Avoid Full-Text Searching
Put together by the librarians at UCLA.
Subject headings are a form of descriptive metadata. At their simplest they may be tags chosen by the authors, but most databases use a controlled vocabulary assigned by professional catalogers (librarians).
The advantage of controlled subject terms is that they're standardized terms which will be assigned to all appropriate content no matter what terminology (or even language) is used by the author. For example, OmniFile Full-Text Mega uses the subject term "Motion Pictures," even if the article uses the words "films," "movies," or "cinema."
Whenever you find a good article in a database, check out the subject headings. If one or more of them look like matches for your topic, re-run your search using those terms--and be sure to specify you want those terms in the subject field. That will ensure the search results are really about that subject and don't just happen to mention those words in passing somehow.
One thing to watch out for: each database has its own controlled vocabulary for subjects. Consequently, the usefulness of the subject headings can vary. And remember that Proquest and EBSCO are not databases. They're online publishing companies that host multiple databases. So even though you can search multiple Proquest databases from the same search box, the subject terms won't be consistent.