如何绘制具有给定形状的 ER 图？

Question

晚上好，关于如何使用以下形状有什么建议吗？

Answer 1

我不认为存在这种图表的库，而且我认为，考虑到上图中单个元素位置的多样性和唯一性，最简单的方法可能是仅使用预定义的形状（例如和rectangle（diamond后者可通过库获得shapes.geometric））并手动添加其他内容。

但是，您当然可以创建自己的形状或使用样式增强现有形状，或者可以\pic像以下示例一样使用 s ，这可能有助于您绘制上图（但您应该熟悉\pics 的一般工作原理）：

\documentclass[border=10pt]{standalone}
\usepackage{tikz}
\usetikzlibrary{shapes.geometric, arrows.meta}

\tikzset{
    % enhanced rectangle
    enhanced rectangle/base/.style={
        draw,
        rectangle,
        align=center,
        minimum width=7em,
        minimum height=2.5em,
        inner sep=5pt,
    },
    enhanced rectangle/text/.initial={},
    pics/enhanced rectangle/.style={
        code={
            \tikzset{#1}
            \node[enhanced rectangle/base] (-base) at (0,0) {
                \pgfkeysvalueof{/tikz/enhanced rectangle/text}
            };
            \tikzset{enhanced node additions/construction}
        }
    },
    % enhanced diamond
    enhanced diamond/base/.style={
        draw,
        diamond,
        align=center,
        minimum width=7.5em,
        minimum height=2em,
        inner sep=1pt,
    },
    enhanced diamond/text/.initial={},
    pics/enhanced diamond/.style={
        code={
            \tikzset{#1}
            \node[enhanced diamond/base] (-base) at (0,0) {
                \pgfkeysvalueof{/tikz/enhanced diamond/text}
            };
            \tikzset{enhanced node additions/construction}
        }
    },
    % enhanced node additions
    enhanced node additions/.initial={},
    enhanced node additions/node/.style={draw, circle, inner sep=2pt},
    enhanced node additions/label/.style={},
    enhanced node additions/radius/.initial={2.25cm and 1.25cm},
    enhanced node additions/connected/.code={
        \tikzset{
            enhanced node additions/connected/path/.style={draw},
            enhanced node additions/connected/node/.style={enhanced node additions/node, fill},
        }
    },
    enhanced node additions/connected/path/.style={},
    enhanced node additions/connected/node/.style={},
    enhanced node additions/connected/start angle/.initial={0},
    enhanced node additions/connected/end angle/.initial={0},
    enhanced node additions/connected/radius/.initial={1.75cm and 0.75cm},
    enhanced node additions/construction/.code={
        \pgfkeysgetvalue{/tikz/enhanced node additions}{\enhanceddiamondadditionslist}
        \ifx\enhanceddiamondadditionslist\empty\else
        \foreach \a/\s/\l [count=\i] in \enhanceddiamondadditionslist {
            \tikzset{
                enhanced node additions/node \i/.style={},
                enhanced node additions/label \i/.style={},
            }
            \node[enhanced node additions/node, enhanced node additions/node \i, label={[enhanced node additions/label, enhanced node additions/label \i]\a:\l}, \s] (-addition node \i) at (\a:\pgfkeysvalueof{/tikz/enhanced node additions/radius}) {};
            \draw (-base) -- (-addition node \i) coordinate[midway] (-addition edge \i);
        }
        \draw (\pgfkeysvalueof{/tikz/enhanced node additions/connected/start angle}:\pgfkeysvalueof{/tikz/enhanced node additions/connected/radius})
            arc (\pgfkeysvalueof{/tikz/enhanced node additions/connected/start angle}:\pgfkeysvalueof{/tikz/enhanced node additions/connected/end angle}:\pgfkeysvalueof{/tikz/enhanced node additions/connected/radius})
            node[enhanced node additions/connected/node] (-addition connect node) {};
        \fi
    },
}

\begin{document}
\begin{tikzpicture}

    \pic (rectangle 1) at (0,0) {enhanced rectangle={
        enhanced rectangle/text={Edizione corso},
        enhanced node additions={
            215//Num. part.,
            280//Data inizio,
            325//Data fine
        },
        enhanced node additions/connected,
        enhanced node additions/connected/start angle=250,
        enhanced node additions/connected/end angle=290,
    }};

    \draw (rectangle 1-base.250) -- ++(0,-2);

    \pic (diamond 1) at (5,0) {enhanced diamond={
        enhanced diamond/text={Foo},
        enhanced node additions={
            135/fill/Ciao,
            45/fill/Hello,
            0//Bye
        },
        enhanced node additions/connected,
        enhanced node additions/connected/start angle=-20,
        enhanced node additions/connected/end angle=65,
    }};

    \node[above] at (diamond 1-addition edge 1) {(1,0)};

    \draw (rectangle 1-base) -- (diamond 1-base) node[above, pos=0.25] {(1,N)};

    \draw[<-, double, double distance=2pt, >={Triangle[length=5pt]}] (diamond 1-base) -- ++(0,-2);

\end{tikzpicture}
\end{document}