  We find a $q$-analog of the following symmetrical identity involving binomial
coefficients $\binom{n}{m}$ and Eulerian numbers $A_{n,m}$, due to Chung,
Graham and Knuth [{\it J. Comb.}, {\bf 1} (2010), 29--38]: {equation*}
\sum_{k\geq 0}\binom{a+b}{k}A_{k,a-1}=\sum_{k\geq 0}\binom{a+b}{k}A_{k,b-1}.
{equation*} We give two proofs, using generating function and bijections,
respectively.
