Longtable issues

Question

I've just started using sharelatex and I read many manuals and previous questions about long tables yet my long table doesn't fit to my document. it is too wide and exit the margins. it doesn't rotate either. I would be glad if you could help me because I don't know where else to look for a solution. That's the text:

\begin{sidewaytable}
\begin{longtable}{|c|c|c|c|}
\hline
Variable &Type/ denomination &Source&Employed in: 
\hline
Compulsory voting 
&Dummy=1 if voting compulsory in country i at time t &Self-created based on IDEA information
&(2a), (3a) 
\hline
Voting age &Minimum age to vote in country i at time t &IDEA&
\hline
Urban population 
&\% population living in cities &WB &(2a), (3a) 
\hline
Gini coefficient&Gini coefficient estimate &WB&(2a) 
\hline
High\_Ten &\% of country i’s GNI held by richest 10\% of population &WB 
\hline
Patents &Patent application from residents of country i at time t &WB 
\hline
Oda &Net ODA received per capita &WB &(2a) 
\hline
Literacy &Literacy rate of population above 15 &WB 
\hline
Life &Life expectancy at birth, in years &WB& 
\hline
Net exports&Exports in current US \$ - Imports in current US \$& Self-created based on WB data &(2a), (3a) 
\hline
Inflation &CPI index, growth rate in country i from t-1 to t, relative to time t &WB&
\hline
Agriculture value added&As a \% of GDP &WB 
\hline
C02 emissions&In tons per capita&WB 
\hline
Domestic credit &To the private sector, as a \% of GDP &WB\\ 
\label{tab2}
\end{longtable}
\end{sidewaytable} 

Answer 1

You do not need a longtable here, and please, please, please, do not use vertical lines:

\documentclass[a4paper]{article}
\usepackage{geometry}
\usepackage{rotating,booktabs,array}
\usepackage{tabulary}
\begin{document}

\begin{sidewaystable}
\setlength\belowcaptionskip{1ex}
\caption{The caption of this table.}
\renewcommand\arraystretch{1.6}
\begin{tabulary}{\linewidth}{LLLL}
\toprule
Variable  & Type/ denomination  & Source & Employed in: \\\midrule
Compulsory voting 
 & Dummy=1 if voting compulsory in country i at time t  & Self-created based on IDEA information
 & (2a), (3a) \\
Voting age  & Minimum age to vote in country i at time t  & IDEA & \\
Urban population 
 & \% population living in cities  & WB  & (2a), (3a) \\
Gini coefficient & Gini coefficient estimate  & WB & (2a) \\
High\_Ten  & \% of country i’s GNI held by richest 10\% of population  & WB \\
Patents  & Patent application from residents of country i at time t  & WB \\
Oda  & Net ODA received per capita  & WB  & (2a) \\
Literacy  & Literacy rate of population above 15  & WB \\
Life  & Life expectancy at birth, in years  & WB &  \\
Net exports & Exports in current US \$ - Imports in current US \$ &  Self-created based on WB data  & (2a), (3a) \\
Inflation  & CPI index, growth rate in country i from t-1 to t, relative to time t  & WB & \\
Agriculture value added & As a \% of GDP  & WB \\
C02 emissions & In tons per capita & WB \\
Domestic credit  & To the private sector, as a \% of GDP  & WB\\ \\\bottomrule
\end{tabulary}
\end{sidewaystable} 
\end{document}

Answer 2

\documentclass[12pt,a4paper]{article}
\usepackage{lscape,ltablex}
\begin{document}

\begin{landscape}
\begin{tabularx}{\linewidth}{|p{8em}|X|p{9em}|p{4em}|}
    \hline
    Variable                & Type/denomination                                                     & Source                                 & Employed in: \\ \hline
    Compulsory voting       & Dummy=1 if voting compulsory in country i at time t                   & Self-created based on IDEA information & (2a), (3a)   \\ \hline
    Voting age              & Minimum age to vote in country i at time t                            & IDEA                                   &              \\ \hline
    Urban population        & \% population living in cities                                        & WB                                     & (2a), (3a)   \\ \hline
    Gini coefficient        & Gini coefficient estimate                                             & WB                                     & (2a)         \\ \hline
    High\_Ten               & \% of country i’s GNI held by richest 10\% of population              & WB                                     &              \\ \hline
    Patents                 & Patent application from residents of country i at time t              & WB                                     &              \\ \hline
    Oda                     & Net ODA received per capita                                           & WB                                     & (2a)         \\ \hline
    Literacy                & Literacy rate of population above 15                                  & WB                                     &              \\ \hline
    Life                    & Life expectancy at birth, in years                                    & WB                                     &              \\ \hline
    Net exports             & Exports in current US \$ - Imports in current US \$                   & Self-created based on WB data          & (2a), (3a)   \\ \hline
    Inflation               & CPI index, growth rate in country i from t-1 to t, relative to time t & WB                                     &              \\ \hline
    Agriculture value added & As a \% of GDP                                                        & WB                                     &              \\ \hline
    C02 emissions           & In tons per capita                                                    & WB                                     &              \\ \hline
    Domestic credit         & To the private sector, as a \% of GDP                                 & WB                                     &              \\ \hline
\end{tabularx}
\end{landscape}

\end{document}