Longtable & tabularx and issues with word wrap

Question

I have a table (tabularx) that is larger than a single page, so I tried using the longtable package. Mytable contains a longer text and when I tried to put the tabularx-table into a "longtable environment" this text goes beyond the page margin - I think because the option "X" isn´t supported anymore. So I looked for other packages and found tabu/longtabu ... but to be honest, it became worse. Can someone please help me?

\documentclass[a4paper,bibliography=totoc,toc=listof,chapterentrydots=on,captions=tableheading,headings=small]{scrbook}

\usepackage{booktabs}
\usepackage{tabularx}
\usepackage{tabulary}
\usepackage{pdflscape}
\usepackage{lscape}
\usepackage{longtable}
\usepackage[figuresright]{rotating}


\usepackage[babel]{csquotes}                                            

\usepackage[language=autobib,
    backend=biber,
    citetracker=true,
    autolang=other,                                                                 
    style=authoryear-comp,                                                          
    maxcitenames=2,maxbibnames=99,                                                  
    uniquename=false,uniquelist=true,                                               
    isbn=false,doi=false,                                                           
    ]{biblatex} 

\usepackage{booktabs}
\newcommand{\tabitem}{~~\llap{\textbullet}~~}   
\usepackage{pdflscape}
\usepackage{lscape}
\usepackage{longtable}
\usepackage{lipsum}
\usepackage{tabularx}


\begin{document}

\begin{table}[hbt]
\footnotesize
\renewcommand{\arraystretch}{1.5}
\caption[title]{\textbf{title}.}
\label{title}
\begin{tabularx}{\linewidth}{p{0.12\linewidth}p{0.15\linewidth}p{0.65\linewidth}}
\toprule
\textbf{principle x}    &   \multicolumn{2}{>{\hsize=\dimexpr2\hsize+2\tabcolsep+\arrayrulewidth\relax}X}{\textbf{This is one of many principles}}\\
                        &   \multicolumn{2}{>{\hsize=\dimexpr2\hsize+2\tabcolsep+\arrayrulewidth\relax}X}{This is a very long text that belongs to the principle mentioned above. I hope that the automatic word wrap is working. } \\
                        &   sub-principle: &  \tabitem subprinciple I \par \tabitem subprinciple II \par \tabitem subprinciple III\\

                        \textbf{principle x}    &   \multicolumn{2}{>{\hsize=\dimexpr2\hsize+2\tabcolsep+\arrayrulewidth\relax}X}{\textbf{This is one of many principles}}\\
                        &   \multicolumn{2}{>{\hsize=\dimexpr2\hsize+2\tabcolsep+\arrayrulewidth\relax}X}{This is a very long text that belongs to the principle mentioned above. I hope that the automatic word wrap is working. } \\
                        &   sub-principle: &  \tabitem subprinciple I \par \tabitem subprinciple II \par \tabitem subprinciple III\\

                        \textbf{principle x}    &   \multicolumn{2}{>{\hsize=\dimexpr2\hsize+2\tabcolsep+\arrayrulewidth\relax}X}{\textbf{This is one of many principles}}\\
                        &   \multicolumn{2}{>{\hsize=\dimexpr2\hsize+2\tabcolsep+\arrayrulewidth\relax}X}{This is a very long text that belongs to the principle mentioned above. I hope that the automatic word wrap is working. } \\
                        &   sub-principle: &  \tabitem subprinciple I \par \tabitem subprinciple II \par \tabitem subprinciple III\\

                        \textbf{principle x}    &   \multicolumn{2}{>{\hsize=\dimexpr2\hsize+2\tabcolsep+\arrayrulewidth\relax}X}{\textbf{This is one of many principles}}\\
                        &   \multicolumn{2}{>{\hsize=\dimexpr2\hsize+2\tabcolsep+\arrayrulewidth\relax}X}{This is a very long text that belongs to the principle mentioned above. I hope that the automatic word wrap is working. } \\
                        &   sub-principle: &  \tabitem subprinciple I \par \tabitem subprinciple II \par \tabitem subprinciple III\\

                        \textbf{principle x}    &   \multicolumn{2}{>{\hsize=\dimexpr2\hsize+2\tabcolsep+\arrayrulewidth\relax}X}{\textbf{This is one of many principles}}\\
                        &   \multicolumn{2}{>{\hsize=\dimexpr2\hsize+2\tabcolsep+\arrayrulewidth\relax}X}{This is a very long text that belongs to the principle mentioned above. I hope that the automatic word wrap is working. } \\
                        &   sub-principle: &  \tabitem subprinciple I \par \tabitem subprinciple II \par \tabitem subprinciple III\\

                        \textbf{principle x}    &   \multicolumn{2}{>{\hsize=\dimexpr2\hsize+2\tabcolsep+\arrayrulewidth\relax}X}{\textbf{This is one of many principles}}\\
                        &   \multicolumn{2}{>{\hsize=\dimexpr2\hsize+2\tabcolsep+\arrayrulewidth\relax}X}{This is a very long text that belongs to the principle mentioned above. I hope that the automatic word wrap is working. } \\
                        &   sub-principle: &  \tabitem subprinciple I \par \tabitem subprinciple II \par \tabitem subprinciple III\\

                        \textbf{principle x}    &   \multicolumn{2}{>{\hsize=\dimexpr2\hsize+2\tabcolsep+\arrayrulewidth\relax}X}{\textbf{This is one of many principles}}\\
                        &   \multicolumn{2}{>{\hsize=\dimexpr2\hsize+2\tabcolsep+\arrayrulewidth\relax}X}{This is a very long text that belongs to the principle mentioned above. I hope that the automatic word wrap is working. } \\
                        &   sub-principle: &  \tabitem subprinciple I \par \tabitem subprinciple II \par \tabitem subprinciple III\\

                        \textbf{principle x}    &   \multicolumn{2}{>{\hsize=\dimexpr2\hsize+2\tabcolsep+\arrayrulewidth\relax}X}{\textbf{This is one of many principles}}\\
                        &   \multicolumn{2}{>{\hsize=\dimexpr2\hsize+2\tabcolsep+\arrayrulewidth\relax}X}{This is a very long text that belongs to the principle mentioned above. I hope that the automatic word wrap is working. } \\
                        &   sub-principle: &  \tabitem subprinciple I \par \tabitem subprinciple II \par \tabitem subprinciple III\\
                        \textbf{principle x}    &   \multicolumn{2}{>{\hsize=\dimexpr2\hsize+2\tabcolsep+\arrayrulewidth\relax}X}{\textbf{This is one of many principles}}\\
                        &   \multicolumn{2}{>{\hsize=\dimexpr2\hsize+2\tabcolsep+\arrayrulewidth\relax}X}{This is a very long text that belongs to the principle mentioned above. I hope that the automatic word wrap is working. } \\
                        &   sub-principle: &  \tabitem subprinciple I \par \tabitem subprinciple II \par \tabitem subprinciple III\\


\bottomrule
\end{tabularx}

\end{table} 

\end{document}

Is it possible to insert this information, too?

\endfirsthead
\multicolumn{3}{l}{{continued from previous page}} \\
\toprule

\endhead
\midrule
\multicolumn{3}{r}{{Continued on next page}} \\
\endfoot
\bottomrule
\endlastfoot

Answer 1

• since you have your table in floating environment (table), which is limited to one page, the inclusion \endfirsthead, \endhead hasn't sense. If this is demand, than you should use longtable , see second example below.

First example: table environment

• i suggest to use tabular* instead of tabularx

From your MWE I made real minimal MWE :) and define \newcommand\mc[1]{...} for \multicolumn:

\documentclass[a4paper,captions=tableheading,headings=small]{scrbook}
\usepackage{booktabs, longtable, tabularx}
\newcommand{\tabitem}{~~\llap{\textbullet}~~}
\newcommand\mc[1]{\multicolumn{2}{p{\dimexpr0.85\linewidth-3\tabcolsep\relax}}{#1}}

\begin{document}
\begin{table}[hbt]
\footnotesize
\renewcommand{\arraystretch}{1.5}
\caption[title]{\textbf{title}.}
    \label{title}
\begin{tabular*}{\linewidth}{>{\bfseries}p{0.15\dimexpr\linewidth-2\tabcolsep\relax}
                                         p{0.15\dimexpr\linewidth-2\tabcolsep\relax}
                                         p{0.70\dimexpr\linewidth-2\tabcolsep\relax}
                             }
    \toprule
principle x     &   \mc{\textbf{This is one of many principles}}\\
                    &   \mc{This is a very long text that belongs to the principle mentioned above. I hope that the automatic word wrap is working. }        \\
                &   sub-principle: 
                    &   \tabitem subprinciple I \par 
                        \tabitem subprinciple II \par 
                        \tabitem subprinciple III                                   \\
principle x     &   \mc{\textbf{This is one of many principles}}\\
                    &   \mc{This is a very long text that belongs to the principle mentioned above. I hope that the automatic word wrap is working. }        \\
                &   sub-principle:
                    &   \tabitem subprinciple I \par
                        \tabitem subprinciple II \par
                        \tabitem subprinciple III                                   \\
principle x     &   \mc{\textbf{This is one of many principles}}\\
                    &   \mc{This is a very long text that belongs to the principle mentioned above. I hope that the automatic word wrap is working. }        \\
                &   sub-principle:
                    &   \tabitem subprinciple I \par
                        \tabitem subprinciple II \par
                        \tabitem subprinciple III                                   \\
\bottomrule
\end{tabular*}
\end{table}
\end{document}

Second example: longtable environment

\documentclass[a4paper,captions=tableheading,headings=small]{scrbook}

\usepackage{booktabs, longtable, tabularx}
\newcommand{\tabitem}{~~\llap{\textbullet}~~}
\newcommand\mc[1]{\multicolumn{2}{p{\dimexpr0.85\linewidth-3\tabcolsep\relax}}{#1}}

\usepackage{lipsum}     % for dummy text in table
\usepackage{showframe}  % for show table layout

\begin{document}

{
\footnotesize
\renewcommand{\arraystretch}{1.5}
    \label{title}
\begin{longtable}{>{\bfseries}p{\dimexpr0.15\linewidth-2\tabcolsep\relax}
                              p{\dimexpr0.15\linewidth-2\tabcolsep\relax}
                              p{\dimexpr0.70\linewidth-2\tabcolsep\relax}
                  }
\caption[title]{\textbf{title}.}
    \label{title}                               \\ 
\toprule             
\endfirsthead
\caption[title]{continued from previous page}   \\
\toprule
\endhead
%
\midrule
\multicolumn{3}{r}{Continued on next page}      \\
\endfoot
\bottomrule
\endlastfoot
%
principle x     &   \mc{\textbf{This is one of many principles}}    \\
                    &   \mc{\lipsum*[1]}                            \\
                &   sub-principle: 
                    &   \tabitem subprinciple I \par 
                        \tabitem subprinciple II \par 
                        \tabitem subprinciple III                   \\
principle x     &   \mc{\textbf{This is one of many principles}}    \\
                    &   \mc{\lipsum*[1]}                            \\
                &   sub-principle:
                    &   \tabitem subprinciple I \par
                        \tabitem subprinciple II \par
                        \tabitem subprinciple III                   \\
principle x     &   \mc{\textbf{This is one of many principles}}    \\
                    &   \mc{\lipsum*[1]}                            \\
                &   sub-principle:
                    &   \tabitem subprinciple I \par
                        \tabitem subprinciple II \par
                        \tabitem subprinciple III                   \\
principle x     &   \mc{\textbf{This is one of many principles}}    \\
                    &   \mc{\lipsum*[1]}                            \\
                &   sub-principle:
                    &   \tabitem subprinciple I \par
                        \tabitem subprinciple II \par
                        \tabitem subprinciple III                   \\
\end{longtable}
}
\end{document}