I&#x27;ve wondered this as well.  However, I couple of notes. CTM is indeed an awesome book, but the idea of language kernel is older. I believe academic papers often start with a minimal language, like the lambda calculus, then show how it can be extended with one feature or another. If I recall correctly, I don&#x27;t think CTM spends any time showing you how to implement these features using a parser&#x2F;interpreter&#x2F;compiler&#x2F;etc.<p>If you are looking for a theoretical model of relational databases, you may look up relational algebra. I&#x27;m sure others will chime in about how sql is not a very good representation of relational algebra; however, if you are not aware of it, RA is certainly something to study.<p>I suspect that you may be referring to a kernel database, the way there are simple implementations of operating systems--written expressly to study how OSes work. I wish something like that existed for databases, but I&#x27;m not aware of it.<p>Finally, there are several text books on relational database management systems. I haven&#x27;t used one in a while so can&#x27;t recommend a specific one. However, these books often show you how to implement various parts of a database, such as b-treee for storage, indexes, how to design a pipeline to implement selection&#x2F;projection&#x2F;group by, etc. Make sure that the book is showing you how to implement a DBMS, not how to design a datamodel.