\begin{table*}[!htb]
\small
\centering
\caption{Performance comparison}
\label{my-label}
\begin{tabular}{|c|c|c|c|c|}
\hline
\multicolumn{2}{|c|}{\multirow{3}{*}{Datasets}} & \multicolumn{3}{c|}{Methods} \\ \cline{3-5}
\multicolumn{2}{|c|}{} & \multicolumn{1}{c|}{\multirow{2}{*}{\begin{tabular}[c]{@{}c@{}}Yang et al. \cite{byang}\end{tabular}}} & \multicolumn{1}{c|}{\multirow{2}{*}{\begin{tabular}[c]{@{}c@{}}Ferrara et al. \cite{pmcc}\end{tabular}}} & \multicolumn{1}{c|}{\multirow{2}{*}{\begin{tabular}[c]{@{}c@{}}Proposed method\end{tabular}}} \\
\multicolumn{2}{|c|}{} & \multicolumn{1}{c|}{} & \multicolumn{1}{c|}{} & \multicolumn{1}{c|}{} \\ \hline
\multirow{4}{*}{\begin{tabular}[c]{@{}c@{}}FV02\end{tabular}}
& DB1 & - & 0 & 0 \\ \cline{2-5}
& DB2 & 5.72 & 6.02 & 1.13 \\ \cline{2-5}
& DB3 & - & 12.43 & 13.39 \\ \cline{2-5}
& DB4 & - & 37 & 32 \\ \hline
\begin{tabular}[c]{@{}c@{}}FV06\end{tabular}
& DB2 & - & 0.03 & 0.09 \\ \hline
\end{tabular}
\end{table*}
\normalsize
\begin{table*}[!htb]
\small
\centering
\caption{Performance comparison}
\label{my-label}
\begin{tabular}{|c|c|c|c|c|c|c|c|c|c|c|}
\hline
\multicolumn{2}{|c|}{\multirow{3}{*}{Datasets}} & \multicolumn{9}{c|}{Methods} \\ \cline{3-11}
\multicolumn{2}{|c|}{} & \multicolumn{1}{c|}{\multirow{2}{*}{\begin{tabular}[c]{@{}c@{}}Ahmad \\ et al. \cite{pairp}\end{tabular}}} & \multicolumn{1}{c|}{\multirow{2}{*}{\begin{tabular}[c]{@{}c@{}}Wang\\ et al. \cite{ditom}\end{tabular}}} & \multicolumn{1}{c|}{\multirow{2}{*}{\begin{tabular}[c]{@{}c@{}}Lee\\ et al. \\ \cite{lmi}\end{tabular}}} & \multicolumn{1}{c|}{\multirow{2}{*}{\begin{tabular}[c]{@{}c@{}}Wong\\ et al. \cite{mlc}\end{tabular}}} & \multicolumn{1}{c|}{\multirow{2}{*}{\begin{tabular}[c]{@{}c@{}}Yang \\ et al. \cite{byang}\end{tabular}}} & \multicolumn{1}{c|}{\multirow{2}{*}{\begin{tabular}[c]{@{}c@{}}Boult \\ et al. \cite{boult}\end{tabular}}} & \multicolumn{1}{c|}{\multirow{2}{*}{\begin{tabular}[c]{@{}c@{}}Ferrara\\ et al. \cite{pmcc}\end{tabular}}} & \multicolumn{1}{c|}{\multirow{2}{*}{\begin{tabular}[c]{@{}c@{}}Ferrara \\ et al. \cite{2pmcc}\end{tabular}}} &
\multicolumn{1}{c|}{\multirow{2}{*}{\begin{tabular}[c]{@{}c@{}}Proposed \\ method\end{tabular}}} \\
\multicolumn{2}{|c|}{} & \multicolumn{1}{c|}{} & \multicolumn{1}{c|}{} & \multicolumn{1}{c|}{} & \multicolumn{1}{c|}{} & \multicolumn{1}{c|}{} & \multicolumn{1}{c|}{} & \multicolumn{1}{c|}{} & \multicolumn{1}{c|}{} & \multicolumn{1}{c|}{} \\ \hline
\multirow{4}{*}{\begin{tabular}[c]{@{}c@{}}FV\\ 02\end{tabular}}
& DB1 & 91 & 13.5 & 13.4 & 14.69 & - & 12.1 & 11.88 & 13.3 & 11.59 \\ \cline{2-11}
& DB2 & 16 & 14 & - & 15.03 & 14.53 & 11.2 & 0.99 & 1.8 & 1.03 \\ \cline{2-11}
& DB3 & 27 & 7.5 & - & - & - & - & 5.24 & 7.8 & 4.02 \\ \cline{2-11}
& DB4 & - & - & - & - & - & - & 4.84 & 6.6 & 3.74 \\ \hline
\begin{tabular}[c]{@{}c@{}}FV\\ 04\end{tabular}
& DB1 & - & - & - & 10.36 & - & - & - & 6.3 & 4.38 \\ \hline
\begin{tabular}[c]{@{}c@{}}FV\\ 06\end{tabular}
& DB2 & - & - & - & - & - & - & 0.17 & 0.3 & 0.19 \\ \hline
\end{tabular}%
\begin{tablenotes}\small
\item $``-"$ indicates that the author(s) have not reported the results or results are reported for partial dataset, in their work.
\end{tablenotes}
\end{table*}
答案1
由于您没有提供生成您要修复的问题的独立、可编译代码，因此无法准确诊断出发生了什么。我的直觉是说明符[htb!]导致了问题。在twocolumn文档中，它们无论如何都是多余的；我会省略它们。
或者，你可以简单地将两个tabular环境及其相关标题放在一 table*环境，使用\bigskip指令来分离材料。
\documentclass[twocolumn]{IEEEtran}
\usepackage[flushleft]{threeparttable}
\usepackage{multirow,array}
\begin{document}
\begin{table*}
\setlength\extrarowheight{2pt} % <-- for a slightly more open 'look'
\centering
% \small %% not needed, as it's automatic with the IEEEtran document class
\caption{Performance comparison} \label{my-label}
\begin{tabular}{|c|c|c|c|c|}
\hline
\multicolumn{2}{|c|}{\multirow{2}{*}{Datasets}} & \multicolumn{3}{c|}{Methods} \\
\cline{3-5}
\multicolumn{2}{|c|}{}
& Yang et~al.\ \cite{byang}
& Ferrara et~al.\ \cite{pmcc}
& Proposed method \\
\hline
\multirow{4}{*}{\begin{tabular}[c]{@{}c@{}}FV02\end{tabular}}
& DB1 & -- & 0 & 0 \\ \cline{2-5}
& DB2 & 5.72 & 6.02 & 1.13 \\ \cline{2-5}
& DB3 & -- & 12.43 & 13.39 \\ \cline{2-5}
& DB4 & -- & 37 & 32 \\ \hline
\begin{tabular}[c]{@{}c@{}}FV06\end{tabular}
& DB2 & -- & 0.03 & 0.09 \\ \hline
\end{tabular}
\bigskip
\begin{threeparttable}
\caption{Performance comparison}
\label{my-label}
\begin{tabular}{|*{11}{c|}}
\hline
\multicolumn{2}{|c|}{\multirow{3}{*}{Datasets}}
& \multicolumn{9}{c|}{Methods} \\
\cline{3-11}
\multicolumn{2}{|c|}{}
& \multicolumn{1}{c|}{\multirow{2}{*}{\begin{tabular}[c]{@{}c@{}}Ahmad \\ et~al.\ \cite{pairp}\end{tabular}}}
& \multicolumn{1}{c|}{\multirow{2}{*}{\begin{tabular}[c]{@{}c@{}}Wang\\ et~al.\ \cite{ditom}\end{tabular}}}
& \multicolumn{1}{c|}{\multirow{2}{*}{\begin{tabular}[c]{@{}c@{}}Lee\\ et~al.\ \cite{lmi}\end{tabular}}}
& \multicolumn{1}{c|}{\multirow{2}{*}{\begin{tabular}[c]{@{}c@{}}Wong\\ et~al.\ \cite{mlc}\end{tabular}}}
& \multicolumn{1}{c|}{\multirow{2}{*}{\begin{tabular}[c]{@{}c@{}}Yang \\ et~al.\ \cite{byang}\end{tabular}}}
& \multicolumn{1}{c|}{\multirow{2}{*}{\begin{tabular}[c]{@{}c@{}}Boult \\ et~al.\ \cite{boult}\end{tabular}}}
& \multicolumn{1}{c|}{\multirow{2}{*}{\begin{tabular}[c]{@{}c@{}}Ferrara\\ et~al.\ \cite{pmcc}\end{tabular}}}
& \multicolumn{1}{c|}{\multirow{2}{*}{\begin{tabular}[c]{@{}c@{}}Ferrara \\ et~al.\ \cite{2pmcc}\end{tabular}}}
& \multicolumn{1}{c|}{\multirow{2}{*}{\begin{tabular}[c]{@{}c@{}}Proposed \\ method\end{tabular}}} \\
\multicolumn{2}{|c|}{} & & & & & & & & & \\
\hline
\multirow{4}{*}{FV02}
& DB1 & 91 & 13.5 & 13.4 & 14.69 & -- & 12.1 & 11.88 & 13.3 & 11.59 \\ \cline{2-11}
& DB2 & 16 & 14& -- & 15.03 & 14.53 & 11.2 & 0.99 & 1.8 & 1.03 \\ \cline{2-11}
& DB3 & 27 & 7.5 & -- & -- & -- & -- & 5.24 & 7.8 & 4.02 \\ \cline{2-11}
& DB4 & -- & -- & -- & -- & -- & -- & 4.84 & 6.6 & 3.74 \\ \hline
FV04 & DB1 & -- & -- & -- & 10.36 & -- & -- & -- & 6.3 & 4.38 \\ \hline
FV06 & DB2 & -- & -- & -- & -- & -- & -- & 0.17 & 0.3 & 0.19 \\ \hline
\end{tabular}
\begin{tablenotes}
\item ``--" indicates that the author(s) have not reported the results or that results are reported for partial dataset in their work.
\end{tablenotes}
\end{threeparttable}
\end{table*}
\end{document}