As a general statement, use an ALIAS after the "from".
I'm not 100% positive if you're using SQL Passthrough from VFP, but as a general statement, I can do this in SQL server

USE ProductionDB
GO

SELECT ProdTable.Name as ProductionName, TestTable.Name as TestName
FROM ProductionTable ProdTable
JOIN TestDB.TestingTable TestTable
WHERE ProdTable.SomeKey = TestTable.SomeKey

Once you have the ALIAS, you shouldn't need to have to reference the 2nd database every time (again, to best of my awareness, but I haven't done anything from VFP->SQL in a long time, so you might want to test to be sure)