A label for multiple equations

Question

The following code gives two examples: The former gives only one label for two equations with a redundant notation "{ ", but the later gives three labels (It should be two?).

Is it possible to give only one label for multiple equations without the notation "{"?

\begin{eqnarray}
  \begin{cases}
A &\sim a,\\
B &\sim b,\\
  \end{cases}
\end{eqnarray}

\begin{align}\label{General}
A &\sim a,\\
B &\sim b,\\
\end{align}

My desired output is the following;

Answer 1

Yes, it is possible by using split environment, and the tags are:

\begin{equation}\label{General}
\begin{split}
A &\sim a,\\
B &\sim b,
\end{split}
\end{equation}

Answer 2

You can use an aligned environment nested within your equation:

\documentclass{article}
\usepackage{amsmath}

\begin{document}
\begin{equation}
    \begin{aligned}
        A &\sim a,\\
        B &\sim b,
    \end{aligned}
\end{equation}
\end{document}