I'm trying to draw a database dependency diagram, similar to the one shown below

(Gaaah! I can't upload images. ASCII art it is then...)

  |      |      |      |      |      |      |
  |      v      |      v      v      v      v
+---+  +---+  +---+  +---+  +---+  +---+  +---+      Lines extend from 1 and 3,
| 1 |  | 2 |  | 3 |  | 4 |  | 5 |  | 6 |  | 7 |      join above 2, and then route
+---+  +---+  +---+  +---+  +---+  +---+  +---+      to all other blocks

I've managed to get the easy bits done, namely drawing the blocks. I assume that I need to create a number of control points that the arrows must move through to 'raise' them above the nodes. What I can't get is to have them drawn nice and square.

Source diagram

Theres also the problem of the junction point above PROJ_NAME (block 2). PROJ_NUM (block 1) and EMP_NUM (block 3) together form a junction, and this junction joins to all the others. My Tikz attempt (although visually very far from what I want) illustrates this (I think?)

Please could someone point me in the right direction? Am I on the right track, is there a way easier method of doing this?

\tikzstyle{line} = [draw, -latex']
\tikzstyle{block} = [rectangle, draw, text centered, rounded corners, 
    minimum height=1.5em,font=\tiny]
\tikzstyle{cntrl} = [node distance=2em, minimum height=0]

    [shorten >=1pt,node distance=0.1em,auto,scale=0.5]        

    \node[block]    (n1)                     {PROJ\_NUM};
    \node[block]    (n2)  [right =of n1]     {PROJ\_NAME};
    \node[block]    (n3)  [right =of n2]     {EMP\_NUM};                                         
    \node[block]    (n4)  [right =of n3]     {EMP\_NAME};
    \node[block]    (n5)  [right =of n4]     {JOB\_CLASS};
    \node[block]    (n6)  [right =of n5]     {CHG\_HOUR};
    \node[block]    (n7)  [right =of n6]     {HOURS};

    \node[cntrl]    (i1)     [above =of n1]                  {};
    \node[cntrl]    (i2)     [above =of n2]                  {};
    \node[cntrl]    (i3)     [above =of n3]                  {};
    \node[cntrl]    (i4)     [above =of n4]                  {};
    \node[cntrl]    (i5)     [above =of n5]                  {};
    \node[cntrl]    (i6)     [above =of n6]                  {};
    \node[cntrl]    (i7)     [above =of n7]                  {};

    \path [line] (n1) .. controls (i1) and (i2) .. (n2);
    \path [line] (n3) .. controls (i3) and (i2) .. (n2);
    \path [line] (i2) .. controls (i2) and (i4) .. (n4);
    \path [line] (i2) .. controls (i2) and (i5) .. (n5);
    \path [line] (i2) .. controls (i2) and (i6) .. (n6);
    \path [line] (i2) .. controls (i2) and (i7) .. (n7);


Links to diagrams that I uploaded. Hopefully the links remain active..

Attempt so far: Tikz attempt so far

4 Answers 4


I read about the rectangle split node yesterday, so this was a chance to experiment. The code is far from perfect, but a good starting point:

\usetikzlibrary{shapes.multipart, calc}

\begin{tikzpicture}[my shape/.style={
rectangle split, rectangle split parts=#1, draw, anchor=center}]
\node [my shape=7, rectangle split horizontal,name=dedi, rectangle split part fill={olive!50, blue!70, olive!50, blue!70}]  at (0,0)
\nodepart{two}   PROJ\_NAME
\nodepart{three} EMP\_NUM
\nodepart{four}  EMP\_NAME
\nodepart{five}  JOB\_CLASS
\nodepart{six}   CHG\_HOUR
\nodepart{seven} HOURS};

\draw[latex-latex, very thick, red!70!black] (dedi.two north) -- ++(0,1) -| (dedi.four north);
\draw[latex-latex, very thick, red!70!black] (dedi.five north) -- ++(0,1) -| (dedi.four north);
\draw[latex-latex, very thick, red!70!black] (dedi.six north) -- ++(0,1) -| (dedi.four north);
\draw[latex-latex, very thick, red!70!black] (dedi.seven north) -- ++(0,1) -| (dedi.four north);
\draw[very thick, red!70!black]              (dedi.one north) -- ++(0,0.5) -| (dedi.three north);
\draw[-latex, very thick, red!70!black]      (dedi.one south) -- ++(0,-0.5) node[below right, text width=3cm] {\scriptsize partial dependancy} -| (dedi.two south);
\draw[-latex, very thick, red!70!black]      ($(dedi.five south) + (0.2,0)$) -- ++(0,-0.5) node[below right, text width=2cm] {\scriptsize Transitive dependancy} -| ($(dedi.six south) + (-0.2,0)$);
\draw[-latex, very thick, red!70!black] (dedi.three south) -- ++(0,-2) -| (dedi.four south);
\draw[-latex, very thick, red!70!black] (dedi.three south) -- ++(0,-2) -| (dedi.five south);
\draw[-latex, very thick, red!70!black] (dedi.three south) -- ++(0,-2) -| node[below left] {\scriptsize partial dependancies} (dedi.six south);
\draw[-latex, very thick, red!70!black] (dedi.three south) -- ++(0,-2) -| (dedi.seven south);


enter image description here


Have you seen the announcement of the tikz-dependency package in comp.text.tex?


  • No, I wasn't aware of the package. Not quite want I want for this scenario, but good to know anyway. Thanks! Jan 21, 2012 at 9:13

for fun and exercise ...

pure tikz solution:

\usetikzlibrary{arrows.meta, chains, positioning, shadows}

node distance = 7mm and 0mm,
  start chain = A going right,
   box/.style = {rectangle, draw, fill=#1,
                 minimum height=7mm, outer sep=0pt,
                 font=\bfseries\sffamily, text=white,
                 drop shadow, on chain=A},
   box/.default = black!30!blue!50,
   lbl/.style = {anchor=north, align=center, inner ysep=2pt,
   arr/.style = {draw=purple, -Triangle, ultra thick},
every edge/.style = {arr}
\node [box=olive]   {PROJ\_NUM};    % A-1
\node [box]         {PROJ\_NAME};
\node [box=olive]   {EMP\_NUM};
\node [box]         {EMP\_NAME};
\node [box]         {JOB\_CLASS};
\node [box]         {CHG\_HOUR};
\node [box]         {HOURS};        % A-7
    \coordinate[above=of A-2]   (aux1);
    \coordinate[above=of aux1]  (aux2);
    \coordinate[below=of A-2]   (aux3);
    \coordinate[below=of aux3]  (aux4);
% arrows above nodes
\draw[arr]  (A-1)   |- (aux1) -| (A-3);
\draw[arr]  (aux2) -| (A-7);
\draw       (aux2)        edge (A-2)
            (aux2 -| A-4) edge (A-4)
            (aux2 -| A-5) edge (A-5)
            (aux2 -| A-6) edge (A-6);
% arrows below nodes
\draw[arr]  (A-1) |- node[lbl,pos=0.75] {Partial\\ dependancy} (aux3) -- (A-2);
\draw[arr]  (A-3) -- (A-3 |- aux4) -| node[lbl,pos=0.25] {Partial dependancy} (A-7);
\draw       (aux4 -| A-4) edge (A-4)
            (aux4 -| A-5) edge (A-5)
            (aux4 -| A-6) edge (A-6);
\draw[arr]  ([xshift= 5mm] A-5.south) -- ([xshift= 5mm] A-5.south |- aux3) -|
        node[lbl,pos=0.25] {Transitive\\ dependancy}
            ([xshift=-5mm] A-6.south);

enter image description here


The style used in Fundamentals of Database Systems by Elmasri and Navathe (ISBN-10: 0136086209) to draw functional dependencies is the following:

enter image description here

It is relatively easy to reproduce using tikz-dependency:


    edge height=2.5ex,
    % edge unit distance=#1*2.5ex, % Another way of controlling the appearance of the edges.
    edge below,
    edge horizontal padding=0,
    edge vertical padding=(#1-1)*3ex,
    text only label, % No need for label for functional dependencies.
    edge slant=0, % Right angles
    rounded corners=0,
    edge style={>=triangle 60} % Change the style of the arrowheads.
    matrix/.append style={column sep=0.4cm} % Adding some distance between the attributes.
\tikzstyle{TxtBook}=[% Style to mimic the textbook Fundamentals of Database Systems.
    column sep=0cm, % No distance between two attributes.
        inner xsep=3ex,
        inner ysep=1ex

        Ename \& \underline{Ssn} \& BDate \& Address \& Dnumber \& Dname \& Dmgr\_ssn \\
    \depedge[lvl=1]{2}{1}{} % Edge are organized by level.

    \begin{deptext}[TxtBook] % Applying the TxtBook style.
        \underline{Ssn} \& \underline{Pnumber} \& Hours \& Ename \& Pname \& Plocation \\



enter image description here

and (closer to the style used in the textbook)

enter image description here

If you are OK with editing the source code of tikz-dependency, you can even patch it as follow (compared with the version 1.2, available at http://ftp.math.purdue.edu/mirrors/ctan.org/graphics/pgf/contrib/tikz-dependency/tikz-dependency.sty ):

> % an explicit offset to compensate the y position of the edge
>    edge start y offset/.code = {\pgfmathsetlengthmacro{\dt@EdgeStartOffsetY}{#1}},
>    edge start y offset = 0,
<       \node (\dt@lastlabel-edge-origin) [coordinate] at ($(#2.\anchorpoint) + (\doff,\dt@startdist) + (\dt@EdgeStartOffsetX,0)$) {};
>       \node (\dt@lastlabel-edge-origin) [coordinate] at ($(#2.\anchorpoint) + (\doff,\dt@startdist) + (\dt@EdgeStartOffsetX,0) + (0,\dt@EdgeStartOffsetY)$) {};
<       \node (\dt@lastlabel-edge-second-corner) [coordinate] at ($(#3.\anchorpoint) + (\dt@EdgeEndOffsetX,0) + (-\dslant,\dt@enddist+\dt@startdist+\ydiff)$) {};
>       \node (\dt@lastlabel-edge-second-corner) [coordinate] at ($(#3.\anchorpoint) + (\dt@EdgeEndOffsetX,0) + (0,\dt@EdgeStartOffsetY) + (-\dslant,\dt@enddist+\dt@startdist+\ydiff)$) {};

and then replace in the previous example

edge vertical padding=(#1-1)*3ex,


edge start y offset=-(#1-1)*3ex,

to get

enter image description here

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