SQLxD Part 8 — WHERE with joined predicates

This is the eighth part of the SQLxD series. For your convenience you can find other parts in the table of contents in Part 1 – XML Transformation

We continue implementing the predicates. Today we will join them to construct logic expressions.

In order to be able to handle complex expressions we need to introduce logic operators. There are three of them: and, or, not. Implementation is rather straightforward:

It is important to note that we do not consider operator precedence here, we assume, that we have operators created correctly. We will get back to this issue when we will handle parsing queries.