This is a very naive (and perhaps unsatisfying) answer, and I haven&#x27;t read CTM so I may misunderstand the real concept of the kernel language, but you may be looking for either the Relational Calculus or Algebra[1][2] or, for less math and more application, straight up database-independent SQL[3].<p>These pretty much describe the underlying set of the things you can do with database systems, and different databases provide different implementations of them with different tradeoffs and abstractions.<p><pre><code>    [1] https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Relational_calculus
    [2] https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Relational_algebra
    [3] https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;SQL</code></pre>