STFT(Short-Time Fourier Transform) & DFT(or FFT) in Matlab

Question

I want to try STFT & FFT using Matlab. What I wonder is STFT of signal computes the result that FFT(DFT) of each windowed signal and I can see the change of each frequency value over time. If I calculate the average of each frequency over the total time, can I get the same amplitude result with the result of the FFT(DFT) of the whole signal?