LaTeX Tables with merged cells & columns

\begin{tabular}{|l|l|l|l|l|l|l|} \hline DataSet & \multicolumn{2}{c}{A} & \multicolumn{2}{c}{B} & \multicolumn{2}{c|}{C} \\ \hline D1 & 2.1\% & 2.1\% & 2.1\% & 2.1\% & 2.1\% & 2.1\% \\ \hline D2 & 11.6\% & 11.6\% & 11.6\% & 11.6\% & 11.6\% & 11.6\% \\ \hline D3 & 5.5\% & 5.5\% & 5.5\% & 5.5\% & 5.5\% & 5.5\% \\ \hline \end{tabular}
\begin{array}{|c|c|} \hline \multicolumn{2}{|c|}{\text{Title}} \\ \hline x & y\\ \hline a & b\\ c & c\\ d & e\\ \hline \end{array}
\rotatebox{90.0}{ {\begin{array}{|c|c|c|}\hline \multicolumn{2}{|c|}\rotatebox{-90.0}{ \text{ 1 } }& \rotatebox{-90.0}{ \text{ 4 } } \\ \hline \rotatebox{-90.0}{ \text{ 5 } }& \rotatebox{-90.0}{ \text{ 3 } } & \rotatebox{-90.0}{ \text{ 44 } }\\ \hline \rotatebox{-90.0}{ \text{ 6 } }& \rotatebox{-90.0}{ \text{ 4 } } & \rotatebox{-90.0}{ \text{ 444 } }\\ \hline \end{array}} }