DB diagram's (entity relationship) - tikz chamfered rectangle with split zones

Question

I try to draw an association type for an entity-relationship diagram. How can I draw a chamfered rectangle with split parts=2 or 3 ? I found this ref : Horizontally enlarged hexagon with TikZ but it doesn't answer completly to my problem. I tried some variations with "chamfered rectangle" and "rectangle split" without success.

How can I draw a figure like this:

Answer 1

OK, this a little too lengthy but essentially it's a mixture of a copy/paste from rectangle split shape + some basic geometry.

I redefined the east and west anchors and the in-between anchors are now accessible via left/right upper/lower bump names. One can further define an encapsulating style to ease the typing of the node settings. Also inner sep needs a little adjusting. The angle is set to 75 via eye-balling but can be also changed.

However it's not perfect. The anchor border is still pointing to the original rectangle split shape and should not be used i.e.

\draw (o) -- (b);

gives wrong results but it gives the correct output if the point is above or below the node since the top and the bottom of this shape is the same with rectangle split.

\documentclass[border=5mm]{standalone}
\usepackage{tikz}
 \usetikzlibrary{shapes.multipart}
\makeatletter
\pgfdeclareshape{chamfered rectangle}{
  \nodeparts{text,two,three,four}
  \inheritsavedanchors[from=rectangle split]
  \inheritanchorborder[from=rectangle split]
  \inheritanchor[from=rectangle split]{center}
  \inheritanchor[from=rectangle split]{north}
  \inheritanchor[from=rectangle split]{north west}
  \inheritanchor[from=rectangle split]{north east}
  \inheritanchor[from=rectangle split]{base}
  \inheritanchor[from=rectangle split]{south}
  \inheritanchor[from=rectangle split]{south west}
  \inheritanchor[from=rectangle split]{south east}
  \inheritanchor[from=rectangle split]{text}
  \inheritanchor[from=rectangle split]{two}
  \inheritanchor[from=rectangle split]{three}
  \inheritanchor[from=rectangle split]{four}
  \inheritanchor[from=rectangle split]{text split west}
  \inheritanchor[from=rectangle split]{two split west}
  \inheritanchor[from=rectangle split]{three split west}
  \inheritanchor[from=rectangle split]{four split west}
  \inheritanchor[from=rectangle split]{text split east}
  \inheritanchor[from=rectangle split]{two split east}
  \inheritanchor[from=rectangle split]{three split east}
  \inheritanchor[from=rectangle split]{four split east}
\savedanchor{\leftbump}{
  \northeast\pgf@xa = \pgf@x \pgf@ya=\pgf@y
  \southwest\pgf@xb = \pgf@x \pgf@yb=\pgf@y
  \pgfmathsetmacro{\vertih}{0.5*(\pgf@ya-\pgf@yb)}
  \pgfmathsetmacro{\horizw}{\vertih/tan(70)}
  \southwest
  \advance\pgf@x by -\horizw pt
  \advance\pgf@y by \vertih pt
}
\savedanchor{\rightbump}{
  \northeast \pgf@xa = \pgf@x \pgf@ya=\pgf@y
  \southwest \pgf@xb = \pgf@x \pgf@yb=\pgf@y
  \pgfmathsetmacro{\vertih}{0.5*(\pgf@ya-\pgf@yb)}
  \pgfmathsetmacro{\horizw}{\vertih/tan(70)}
  \northeast
  \advance\pgf@x by \horizw pt
  \advance\pgf@y by -\vertih pt
}
\savedanchor{\lubump}{
  \northeast\pgf@xa = \pgf@x \pgf@ya=\pgf@y
  \southwest\pgf@xb = \pgf@x \pgf@yb=\pgf@y
  \pgf@lib@sh@rs@anchor@one@split@west
  \pgfmathsetmacro{\vertih}{(\pgf@ya-\pgf@y)}
  \pgfmathsetmacro{\horizw}{\vertih/tan(70)}
  \pgfpoint{\pgf@xb}{\pgf@ya}
  \advance\pgf@x by -\horizw pt
  \advance\pgf@y by -\vertih pt
}
\savedanchor{\llbump}{
  \northeast\pgf@xa = \pgf@x \pgf@ya=\pgf@y
  \southwest\pgf@xb = \pgf@x \pgf@yb=\pgf@y
  \pgf@lib@sh@rs@anchor@three@split@west
  \pgfmathsetmacro{\vertih}{(\pgf@y-\pgf@yb)}
  \pgfmathsetmacro{\horizw}{\vertih/tan(70)}
  \southwest
  \advance\pgf@x by -\horizw pt
  \advance\pgf@y by \vertih pt
}
\savedanchor{\rubump}{
  \northeast\pgf@xa = \pgf@x \pgf@ya=\pgf@y
  \southwest\pgf@xb = \pgf@x \pgf@yb=\pgf@y
  \pgf@lib@sh@rs@anchor@one@split@west
  \pgfmathsetmacro{\vertih}{(\pgf@ya-\pgf@y)}
  \pgfmathsetmacro{\horizw}{\vertih/tan(70)}
  \northeast
  \advance\pgf@x by \horizw pt
  \advance\pgf@y by -\vertih pt
}
\savedanchor{\rlbump}{
  \northeast\pgf@xa = \pgf@x \pgf@ya=\pgf@y
  \southwest\pgf@xb = \pgf@x \pgf@yb=\pgf@y
  \pgf@lib@sh@rs@anchor@three@split@west
  \pgfmathsetmacro{\vertih}{(\pgf@y-\pgf@yb)}
  \pgfmathsetmacro{\horizw}{\vertih/tan(70)}
  \pgfpoint{\pgf@xa}{\pgf@yb}
  \advance\pgf@x by \horizw pt
  \advance\pgf@y by \vertih pt
}

\anchor{east}{\rightbump}
\anchor{west}{\leftbump}
\anchor{left upper bump}{\lubump}
\anchor{left lower bump}{\llbump}
\anchor{right upper bump}{\rubump}
\anchor{right lower bump}{\rlbump}
  \backgroundpath{
  \rectanglesplitparameters
  \northeast
  \pgf@xa = \pgf@x \pgf@ya=\pgf@y
  \centerpoint
  \pgf@xc = \pgf@x \pgf@yc=\pgf@y
  \southwest
  \pgf@xb = \pgf@x \pgf@yb=\pgf@y
\pgfmathsetmacro{\vertih}{0.5*(\pgf@ya-\pgf@yb)}
\pgfmathsetmacro{\horizw}{\vertih/tan(70)}
  \pgfpathmoveto{\northeast}
  \pgflineto{\pgfpoint{\pgf@xb}{\pgf@ya}}
  \pgflineto{\leftbump}
  \pgflineto{\southwest}
\pgflineto{\pgfpoint{\pgf@xa}{\pgf@yb}}
\pgflineto{\rightbump}
\pgfclosepath
\pgfmoveto{\lubump}\pgflineto{\rubump}
\pgfmoveto{\llbump}\pgflineto{\rlbump}
  }
}
\makeatother
\begin{document}
\begin{tikzpicture}
\node (o) at (0,0) {0};
\node[chamfered rectangle,rectangle split part align={center,left,left,center},draw,inner sep=2pt] (a) at (0,3) {
\verb|COMPTE|
\nodepart{two} \verb|NUM_COMPTE |
\nodepart{three} \verb|SOLDE|
\nodepart{four} \verb|id:NUM_COMPTE|
};
\node[chamfered rectangle,rectangle split part align={center,left,left,center},draw] (b) at (3,0) {
\verb|AA|
\nodepart{two} \verb|NUM_AA |
\nodepart{three} \verb|RAND|
\nodepart{four} \verb|id:NUM_AA|
};
\draw (a.right lower bump) -- (b.left upper bump);
\draw[-latex] (o) -- (b.left lower bump);
\end{tikzpicture}
\end{document}

Following Tom's cue, here are the anchors that are defined in the custom shape, one can add/remove more anchors simply following the copy/paste pattern. However <nodepartnumber> split east/west anchor would still be defined as in the original version but I don't think they would be needed in this particular case.

Answer 2

Here you go: a chamfered rectangle which defines several coordinates that you can use:

\documentclass[parskip]{scrartcl}
\usepackage[margin=15mm]{geometry}
\usepackage{tikz}
\usetikzlibrary{shapes,calc,arrows}

\newcommand{\chamrec}[8]{% width, height, name, 1st, 2nd, 3rd, x, y
    \pgfmathsetmacro{\ind}{#2/4}
    \begin{scope}[xshift=#7,yshift=#8]
        \draw (\ind,0) coordinate (#3_bl) -- (#1-\ind,0) coordinate (#3_br) -- (#1,#2/2) coordinate (#3_r) -- (#1-\ind,#2) coordinate (#3_tr) -- (\ind,#2)  coordinate (#3_tl) -- (0,#2/2) coordinate (#3_l) -- cycle;
        \coordinate (#3_tlm) at ($0.5*(#3_tl)+0.5*(#3_l)$);
        \coordinate (#3_t) at ($0.5*(#3_tl)+0.5*(#3_tr)$);
        \coordinate (#3_trm) at ($0.5*(#3_tr)+0.5*(#3_r)$);
        \coordinate (#3_brm) at ($0.5*(#3_br)+0.5*(#3_r)$);
        \coordinate (#3_b) at ($0.5*(#3_br)+0.5*(#3_bl)$);
        \coordinate (#3_blm) at ($0.5*(#3_bl)+0.5*(#3_l)$);
        \coordinate (#3_sls) at ($0.5*(#3_bl)+0.5*(#3_tl)$);
        \pgfmathsetmacro{\txt}{(#1-2*\ind-0.1)*1cm}
        \draw (#3_tlm) -- (#3_trm);
        \draw (#3_blm) -- (#3_brm);
        \node[below] at (#3_t) {#4};
        \node[right,text width=\txt] at (#3_sls) {#5};
        \node[above right] at (#3_bl) {#6};
    \end{scope} 
}

\begin{document}

\begin{tikzpicture}
    \chamrec{6}{2}{first}{Red}{Blue Blue Blue Blue Blue Blue Blue Blue}{Yellow}{0}{0}
    \chamrec{6}{2}{second}{Ice}{Water}{Steam}{0}{3cm}
    \chamrec{6}{2}{third}{Crash}{\&}{Burn}{8cm}{1.5cm}
    \draw[-latex,red,very thick] (first_t) -- node[right] {asdf} (second_b);
    \draw[-latex,thick] (first_trm) -- node[below,sloped] {wasd} (third_blm);
    \draw[latex-latex,ultra thick,blue] (third_tlm) -- node[below,sloped] {\#ACDC} (second_brm);
\end{tikzpicture}

\begin{tikzpicture}
    \chamrec{6}{6}{show}{First}{Second}{Third}{0}{0}
    \foreach \x in {l,tlm,tl,t,tr,trm,r,brm,br,b,bl,blm,sls}
    {   \node[circle,draw,fill=white] at (show_\x) {\tiny\x};
    }
\end{tikzpicture}

\end{document}