When you change databases without logging off, Ovid will display the Re-Run Searches Page. If a term has an equivalent See Term, that term is searched instead. This enhancement provides for more accurate results when searches are run against databases with controlled vocabulary characteristics, and ensures that saved searches remain effective in databases with different vocabularies. However, a search in one database may need to be modified to work well in another database. This is especially true when switching between databases addressing different disciplines.
Databases also use different fields.
A field searched in one database may not even exist in the other database. Occasionally searches cannot be processed and will be ignored by Ovid. When you change databases, you may need to experiment with different vocabulary and field names to obtain the best possible retrieval in each database.