documentclass{standalone}
usepackage{pgfplots}
usepgfplotslibrary{dateplot}
pgfplotsset{compat=1.12}
usepackage{filecontents}
begin{filecontents*}{data.csv}
date,value
2015-01-01, 3.2
2015-01-02, 6.5
2015-01-04, 6.8
end{filecontents*}
begin{document}
begin{tikzpicture}
centering
begin{axis}[
    date coordinates in=x,
    xticklabel={day-month-year},
    x tick label style={rotate=45,anchor=north east},
    date ZERO=2015-01-01,
    grid=both,
    enlarge x limits=false,
    xlabel={Date (day-month-year)},
    ylabel={Value},
]
addplot table [x=date, y=value, col sep=comma] {data.csv};
end{axis}
end{tikzpicture}
end{document}

documentclass{standalone}
usepackage{pgfplots}
usepackage{etoolbox}
usepgfplotslibrary{dateplot}
pgfplotsset{compat=1.12}
usepackage{filecontents}

begin{filecontents*}{data.csv}
date,value
2015-01-01, 3.2
2015-01-02, 6.5
2015-01-04, 6.8
end{filecontents*}
begin{document}
begin{tikzpicture}
centering
begin{axis}[
    date coordinates in=x,
    xticklabel={day-month-year},
    x tick label style={rotate=45,anchor=north east},
    date ZERO=2015-01-01,
    grid=both,
    enlarge x limits=false,
    xlabel={Date (day-month-year)},
    ylabel={Value},
    xticklabel={%
        ifcsdef{Tick Used tick}{}{%
            tick%
            csxdef{Tick Used tick}{}%
        }%
    },
]
addplot table [x=date, y=value, col sep=comma] {data.csv};
end{axis}
end{tikzpicture}
end{document}