# Crow's Foot ERM in nice way

I found this post about how to do Crow's Foot ERM Diagrams with Tikz, but it looks strange because the entity is outside the frame. However, it worked.

Then I found this even nicer version and tried to combine it, but sadly I'm not able to find out why it doesn't work. I'm not able to print two entities side by side and connect them with a crow's foot wire. They always print over each other...

How can I have both the lines and the style?

\documentclass{article}

\usepackage{tikz}
\usetikzlibrary{shapes.multipart}
\usetikzlibrary{matrix}
\usetikzlibrary{positioning}
\usetikzlibrary{calc}

\tikzset{
entity/.code={
\tikzset{
rounded corners,
name=#1,
inner sep=2pt,
every entity/.try,
}%
\def\entityname{#1}%
},
entity anchor/.style={matrix anchor=#1},
every entity/.style={
draw,
},
every property/.style={
inner xsep=0.20cm, inner ysep=0.075cm, anchor=west, text width=1.75in
}
}
\def\property#1{\node[name=\entityname-#1, every property/.try]{\propertysplit#1;};}
\def\properties{\begingroup\catcode\_=11\relax\processproperties}
\def\processproperties#1{\endgroup%
\gdef\propertycode{}%
\foreach \p in {#1}{%
\expandafter\expandafter\expandafter\gdef\expandafter\expandafter\expandafter\propertycode%
\expandafter\expandafter\expandafter{\expandafter\propertycode\expandafter\property\expandafter{\p}\\}%
}%
\propertycode%
}
\def\propertysplit#1:#2;{#1:\hfill#2}

\def\entitynamenode{%
\node[every entity name/.try] (\entityname-name) {\entityname};
\draw (\entityname-name.south west) -- (\entityname-name.south east);
\\[1ex]
}
\tikzset{
every entity name/.style={every property/.try, align=center}
}
\begin{document}
\begin{tikzpicture}[every node/.style={font=\ttfamily}, node distance=0.5in]
\matrix (m1) [entity=Employee] {
\entitynamenode
\properties{
Name :  varchar(255),
LastName :  varchar(255)
}
};
\matrix (m2) [entity=Student] {
\entitynamenode
\properties{
Name :  varchar(255),
LastName :  varchar(255)
}
};
\draw [->] (m1) -- (m2); % <-- it break's here...
\end{tikzpicture}
\end{document}


Edit: this is a Crow's Foot Notation for visualizing IT Database structures:

• A matrix, like a node, will be placed at (0,0) unless you say otherwise. Say \matrix (m1) [...] {...}; and then \matrix (m2) [entity=Student,right=of m1] {...};. I don't know what a crow's foot wire is, but to draw e.g. an arrow between the two, \draw [->] (m1) -- (m2); Apr 24 '17 at 20:00
• This does not work on my side. It breaks where i try to \draw [->] (m1) -- (m2); the MWE is updated you can copy paste it to see what hapens. I still don't understand why this -- tex.stackexchange.com/questions/141797/… -- post doesn't need that (m1) definition... Apr 29 '17 at 5:30
• Then your code doesn't do the same thing as the code in that question. For one thing, you're missing the one to omany style, but I haven't looked for other differences. As for naming the matrices manually, seems I had the wrong order, you need \matrix [entity=Employee] (m1) and \matrix [right=of m1,entity=Student] (m2), i.e. the name after the options. Apr 29 '17 at 5:44

Since your MWE it's above my level of knowledge, I propose a solution with a pic (entity) with a tabular inside.

The arguments of the pic are 3: name of the node, name of the entity and the rows of the tabular (maybe it's more elegant to have the complete tabular as the third argument, in this case, you can define two new column types in order to avoid typing them all the times).

The code for the one to many, etc. is taken from one of the posts you linked.

I've added another entity just to show that the size of the entity varies according to the number of rows you put in the tabular.

\documentclass{article}
\usepackage{array}
\renewcommand{\arraystretch}{1.1}
\usepackage{tikz}
\usetikzlibrary{shapes.multipart}
\usetikzlibrary{positioning}
\usetikzlibrary{calc}

% code for "one to omany", etc. is taken from https://tex.stackexchange.com/q/141797/101651
\makeatletter
\pgfarrowsdeclare{crow's foot}{crow's foot}
{
\pgfarrowsleftextend{+-.5\pgflinewidth}%
\pgfarrowsrightextend{+.5\pgflinewidth}%
}
{
\pgfutil@tempdima=0.6pt%
\pgfsetdash{}{+0pt}%
\pgfsetmiterjoin%
\pgfpathmoveto{\pgfqpoint{0pt}{-9\pgfutil@tempdima}}%
\pgfpathlineto{\pgfqpoint{-13\pgfutil@tempdima}{0pt}}%
\pgfpathlineto{\pgfqpoint{0pt}{9\pgfutil@tempdima}}%
\pgfpathmoveto{\pgfqpoint{0\pgfutil@tempdima}{0\pgfutil@tempdima}}%
\pgfpathmoveto{\pgfqpoint{-8pt}{-6pt}}%
\pgfpathlineto{\pgfqpoint{-8pt}{-6pt}}%
\pgfpathlineto{\pgfqpoint{-8pt}{6pt}}%
\pgfusepathqstroke%
}

\pgfarrowsdeclare{omany}{omany}
{
\pgfarrowsleftextend{+-.5\pgflinewidth}%
\pgfarrowsrightextend{+.5\pgflinewidth}%
}
{
\pgfutil@tempdima=0.6pt%
\pgfsetdash{}{+0pt}%
\pgfsetmiterjoin%
\pgfpathmoveto{\pgfqpoint{0pt}{-9\pgfutil@tempdima}}%
\pgfpathlineto{\pgfqpoint{-13\pgfutil@tempdima}{0pt}}%
\pgfpathlineto{\pgfqpoint{0pt}{9\pgfutil@tempdima}}%
\pgfpathmoveto{\pgfqpoint{0\pgfutil@tempdima}{0\pgfutil@tempdima}}%
\pgfpathmoveto{\pgfqpoint{0\pgfutil@tempdima}{0\pgfutil@tempdima}}%
\pgfpathmoveto{\pgfqpoint{-6pt}{-6pt}}%
\pgfpathcircle{\pgfpoint{-11.5pt}{0}} {3.5pt}
\pgfusepathqstroke%
}

\pgfarrowsdeclare{one}{one}
{
\pgfarrowsleftextend{+-.5\pgflinewidth}%
\pgfarrowsrightextend{+.5\pgflinewidth}%
}
{
\pgfutil@tempdima=0.6pt%
\pgfsetdash{}{+0pt}%
\pgfsetmiterjoin%
\pgfpathmoveto{\pgfqpoint{0\pgfutil@tempdima}{0\pgfutil@tempdima}}%
\pgfpathmoveto{\pgfqpoint{-6pt}{-6pt}}%
\pgfpathlineto{\pgfqpoint{-6pt}{-6pt}}%
\pgfpathlineto{\pgfqpoint{-6pt}{6pt}}%
\pgfpathmoveto{\pgfqpoint{0\pgfutil@tempdima}{0\pgfutil@tempdima}}%
\pgfpathmoveto{\pgfqpoint{-8pt}{-6pt}}%
\pgfpathlineto{\pgfqpoint{-8pt}{-6pt}}%
\pgfpathlineto{\pgfqpoint{-8pt}{6pt}}%
\pgfusepathqstroke%
}
\makeatother

\tikzset{%
pics/entity/.style n args={3}{code={%
\node[draw, blue,
rounded corners},
rounded corners,
font=\ttfamily\footnotesize,
rectangle
] (#1)
{\color{black}\begin{tabular}{>{\raggedright\arraybackslash}p{4.5em}>{\raggedleft\arraybackslash}p{6em}}
#3
\end{tabular}
};%
\node[font=\ttfamily\footnotesize,
text height=1.5ex,text depth=.25ex,
above =0pt of #1
]
{#2};%
}},
pics/entitysimple/.style n args={3}{code={%
\node[draw, rounded corners,
rectangle split,
rectangle split parts=2,
font=\ttfamily\footnotesize,
text height=1.5ex,text depth=.25ex
] (#1)
{#2 \nodepart{second}
\begin{tabular}{>{\raggedright\arraybackslash}p{4.5em}>{\raggedleft\arraybackslash}p{6em}}
#3
\end{tabular}
};%
}},
zig zag to/.style={
to path={(\tikztostart) -| ($(\tikztostart)!#1!(\tikztotarget)$) |- (\tikztotarget)}
},
zig zag to/.default=0.5,
one to one/.style={
one-one, zig zag to
},
one to many/.style={
one-crow's foot, zig zag to,
},
one to omany/.style={
one-omany, zig zag to
},
many to one/.style={
crow's foot-one, zig zag to
},
many to many/.style={
crow's foot-crow's foot, zig zag to
},
}
\begin{document}
\noindent Version like your colored image:
\begin{center}
\begin{tikzpicture}
\pic {entity={empl}{Employee}{%
Name: & varchar(255) \\
LastName: & varchar(255) \\
}};
\pic[right=7em of empl] {entity={stud}{Student}{%
Name: & varchar(255) \\
LastName: & varchar(255) \\
}};
\pic[below=12ex of stud] {entity={thesis}{Thesis}{%
Title: & \textcolor{red}{(PK)} \\
Year: & numeric(4) \\
}};
\draw[one to omany] ($(empl.north east)-(0,10pt)$) -- node[above]{\footnotesize\texttt{teaches}} ($(stud.north west)-(0,10pt)$);
\draw[one to one] ($(stud.south)+(50pt,0)$) -- node[left]{\footnotesize\texttt{writes}} ($(thesis.north)+(50pt,0)$);
\draw[one to many] ($(empl.south)+(30pt,0)$) |- node[left, yshift=36pt] {\footnotesize\texttt{supervises}} ($(thesis.west)+(0,4pt)$);
\end{tikzpicture}
\end{center}
\begin{center}
\begin{tikzpicture}
\pic {entitysimple={empl}{Employee}{%
Name: & varchar(255) \\
LastName: & varchar(255) \\
}};
\pic[right=7em of empl] {entitysimple={stud}{Student}{%
Name: & varchar(255) \\
LastName: & varchar(255) \\
}};
\pic[below=12ex of stud] {entitysimple={thesis}{Thesis}{%
Title: & \textcolor{red}{(PK)} \\
Year: & numeric(4) \\
}};
\draw[one to omany] (empl.east) -- node[above]{\footnotesize\texttt{teaches}} (stud.west);
\draw[one to one] (stud.south) -- node[left]{\footnotesize\texttt{writes}} (thesis.north);
\draw[one to many] (empl.south) |- node[left, yshift=44pt, xshift=-2pt] {\footnotesize\texttt{supervises}} (thesis.west);
\end{tikzpicture}
\end{center}
\end{document}
`

• This is exactly what i searched for. verry nice. It only seams to interact with some other drawings in my huge document. questioned in a new thread - tex.stackexchange.com/questions/367454/… Thanks a lot for the Help! Apr 30 '17 at 10:48