This is the eighteenth part of the SQLxD series. For your convenience you can find other parts in the table of contents in Part 1 – XML Transformation Last time we saw tests for aggregates. Today we are going to implement expressions. We can compare columns with different value types: numbers, dates, strings. However, it … Continue reading SQLxD Part 18 — Expressions

This is the seventeenth part of the SQLxD series. For your convenience you can find other parts in the table of contents in Part 1 – XML Transformation Last time we implemented aggregates, today we test them. Here are the snippets: That’s all. In the next part we will implement various functions for dates, strings, … Continue reading SQLxD Part 17 — Tests for aggregates

This is the sixteenth part of the SQLxD series. For your convenience you can find other parts in the table of contents in Part 1 – XML Transformation Today we implement various aggregates. Let’s start with the interface: We can see that the aggregate returns one cell for whole relation. You might wonder why is … Continue reading SQLxD Part 16 — Aggregates

This is the fifteenth part of the SQLxD series. For your convenience you can find other parts in the table of contents in Part 1 – XML Transformation Last time we implemented grouping, today we focus on ordering. These two operations are very similar. First, we need to know which column we use for sorting … Continue reading SQLxD Part 15 — Ordering

This is the fourteenth part of the SQLxD series. For your convenience you can find other parts in the table of contents in Part 1 – XML Transformation Today we implement grouping. Since we can group in multiple ways, we need to have grouping sets: Grouping set is just a set of columns which we … Continue reading SQLxD Part 14 — Grouping