Csdrhrt

My Code:

documentclass[12pt,a4paper]{article}

usepackage[utf8]{vietnam}

usepackage{amsmath,amssymb}

usepackage{mathptmx} 

usepackage{graphicx}

usepackage[margin=2.1cm]{geometry}



usepackage{tabls}

usepackage{diagbox,pict2e}



begin{document}



begin{tabular}{|*{5}{c}|}

    hline

    2007 & 2008 & 2009 & 2010 & 2011\

    hline

    08.04 & 23.03 & 12.04 & 04.04 & 24.04 \

    27.05 & 11.05 & 31.05 & 23.05 & 12.06 \

    hline

end{tabular}

end{document}

The result:

How to the output file as the following:

Is the tabls package obsolete?

You can use the dirty hack of using rule{depth}{width}{height} in particular row to change the appearance of the row itself.

documentclass{article}

%https://tex.stackexchange.com/questions/232202/how-to-add-extra-space-inside-of-a-table

begin{document}

    begin{tabular}{|*{5}{c}|}

    hline

    2007 & 2008 & 2009 & 2010 & 2011rule[-2ex]{0pt}{6ex}\

    hline

    08.04 & 23.03 & 12.04 & 04.04 & 24.04 rule[1ex]{0pt}{3ex}\

    27.05 & 11.05 & 31.05 & 23.05 & 12.06 rule[-2ex]{0pt}{3ex}\

    hline

end{tabular}

end{document}

with which you can get

Note: I dont know about the status regarding the package tabls. IMO, it should be a second question instead.

I'm not sure I understand your question 100%. Personally, I feel tables made with the booktabs package look more modern. Here's an example

documentclass[12pt,a4paper]{article}

usepackage[utf8]{vietnam}

usepackage{amsmath,amssymb}

usepackage{mathptmx} 

usepackage{graphicx}

usepackage[margin=2.1cm]{geometry}



usepackage{booktabs}

usepackage{diagbox,pict2e}



begin{document}



    begin{tabular}{*{5}{c}}

        toprule

        2007 & 2008 & 2009 & 2010 & 2011\

        midrule

        08.04 & 23.03 & 12.04 & 04.04 & 24.04 \

        27.05 & 11.05 & 31.05 & 23.05 & 12.06 \

        bottomrule

    end{tabular}

end{document}