Doing VLOOKUP on Oracle data in Excel

I download and work with a lot of data at work which I get through SQL from our oracle tables. When this data is returned to Excel, I cannot perform FIND, or VLOOKUP funtions on it. I have found one way around this: I multiply any numbers that are returned by 1, then Excel can find them when I do VLOOKUPs or FIND functions. However a lot of the data I deal with has letters in the field along with numbers, so the multiply by one trick won't work. Is there some kind of formatting issue going on here? Why can't excel find the numbers when they are pulled from oracle? Is there an easy solution to this that I am overseeing?