Multicolumns in one table instead of three separate tables - latex

Question

I want table in overleaf with three main columns in one table. I used muticolumn, but instead of one table with three columns it comes as three tables. It comes like this:
Here is the code for it. I am trying to remove the spaces between columns and make it look like one table. Any help appreciated
\begin{table}[h!]
\center
\setlength{\tabcolsep}{2pt}
\caption{ Model of Dataset I Tested on Dataset III}
\label{my-label7}
\begin{tabular}{|l|l|l|l|l|l|l|l|l|l|l|l|l|l|l|l|l|l|l|l|l|l|l|}
\hline
\multicolumn{14}{|c|}{Model Based Approach } \\
\hline
Hosts & A & B & D & G & H & I & J & L & M & N & P & Q & R \\ \hline
DR & 1 & 0.85 & 0.6 & 1 & 1 & 1 & 1 & 1 & 1 & 1 & 1 & 1 & 1 \\
\hline
FPR & 0.04 & 0 & 0 & 0 & 0 & 0 & 0 &0 & 0 & 0 & 0 & 0 &
0 \\ \hline
\end{tabular}
\begin{tabular}{|l|l|l|l|l|l|l|}
\hline
\multicolumn{5}{|c|}{Instance Based Approach} \\
\hline
C & E & F & K & O \\ \hline
1 & 0.79 & 1 & 1 & 1 \\ \hline
0 & 0 & 0.5 & 0 & 0 \\ \hline
\end{tabular}
\begin{tabular}{|l|l|}
\hline
\multicolumn{1}{|c|}{Average} \\
\hline
All \\ \hline
\textbf{0.95} \\ \hline
\textbf{0.03} \\ \hline
\end{tabular}
\end{table}

Answer 1

The table is set as three different tables because it is set using three separate tabulars. Below I've combined them, but also used [booktabs](//ctan.org/pkg/booktabs for a less line-based approach.
\documentclass{article}
\usepackage{booktabs,makecell}
\begin{document}
\begin{table}
\centering
\setlength{\tabcolsep}{2pt}
\caption{Model of Dataset I Tested on Dataset III}
\begin{tabular}{ *{20}{l} }
\toprule
& \multicolumn{13}{c}{Model Based Approach} &
\multicolumn{5}{c}{\makecell[b]{Instance Based \\ Approach}} &
\multicolumn{1}{c}{Average} \\
\cmidrule(lr){2-14}
\cmidrule(lr){15-19}
\cmidrule(lr){20-20}
Hosts & A & B & D & G & H & I & J & L & M & N & P & Q & R &
C & E & F & K & O &
All \\
DR & 1 & 0.85 & 0.6 & 1 & 1 & 1 & 1 & 1 & 1 & 1 & 1 & 1 & 1 &
1 & 0.79 & 1 & 1 & 1 &
\textbf{0.95} \\
FPR & 0.04 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 &
0 & 0 & 0.5 & 0 & 0 &
\textbf{0.03} \\
\bottomrule
\end{tabular}
\end{table}
\end{document}