How to place a table on a new page with landscape orientation without clearing the current page?

Similar like my answer to How to wrap text around landscape page I would use \afterpage from the afterpage package to place the table at the next page of where it was declared. Here a non-floating replacement of table is used instead, e.g. the \captionof{table}{...} is used (capt-of or caption) package.

One issue are potential other tables which should be flushed beforehand. Otherwise the non-floating table replacement might appear earlier.

\documentclass{article}

\usepackage{pdflscape}
\usepackage{afterpage}
\usepackage{capt-of}% or use the larger `caption` package

\usepackage{lipsum}% dummy text
\begin{document}
\lipsum % Text before
\afterpage{%
    \clearpage% Flush earlier floats (otherwise order might not be correct)
    \thispagestyle{empty}% empty page style (?)
    \begin{landscape}% Landscape page
        \centering % Center table
        \begin{tabular}{llll}
            A & B & C & D \\
        \end{tabular}
        \captionof{table}{Table caption}% Add 'table' caption
    \end{landscape}
    \clearpage% Flush page
}
\lipsum % Text after
\end{document}

You could use the sidewaystable environment from the rotating package; a little example:

\documentclass{article}
\usepackage{rotating}

\begin{document}
text text text text
\begin{sidewaystable}
  \centering
  \rule{3cm}{4cm}% to simulate a table
  \caption{A rotated table}
  \label{tab:test}
\end{sidewaystable}
text text text
\end{document}