Latex: change row color of table

An example here:

\usepackage[table]{xcolor}
(if you use pdflatex and/or beamer, perhaps you need to transit 'table' by
\documentclass[xcolor=table..]{beamer} or you will have an error like:
! LaTeX Error: Option clash for package xcolor.
)

\begin{table}
\centering
\rowcolors{2}{gray!10}{}\tiny
\begin{tabular}{c||cc|cc}\hline\hline
....
\end{tabular}
\caption{...}
\end{table}