
Five DAX Patterns Every Power BI Analyst Should Know
Five practical DAX patterns for Power BI: measures vs. calculated columns, year-to-date and year-over-year time intelligence, running totals, and dynamic ranking with RANKX.
Knowledge hub
Tutorials, case studies, and notes on analytics engineering and BI.

Five practical DAX patterns for Power BI: measures vs. calculated columns, year-to-date and year-over-year time intelligence, running totals, and dynamic ranking with RANKX.

What dbt actually does and why teams adopt it: the staging, intermediate, and marts layering pattern, a worked model, and how tests and docs turn raw SQL into a trustworthy product.

SQL window functions explained with runnable examples: running totals, ranking with row_number, rank, and dense_rank, and period-over-period comparisons with lag and lead.
Most wasted analyst effort comes from the gap between the request someone makes and the decision they are trying to make. Four questions that close it, the short brief that converts your assumptions into theirs, and how to handle the answers you will actually get.
The same formula written two ways behaves completely differently. Row context versus filter context, why averaging a margin column is wrong, the memory cost of stored columns, and a one-sentence rule for choosing correctly.
When a sales rep changes team, should last quarter's numbers move with them? That question decides your dimension design. Type 1 versus Type 2 in plain terms, the join mistake that silently loses rows, and how dbt snapshots handle it.
Why the notebook that produced your headline number only works on your laptop, and the hour of work that fixes it: restart-and-run-all, extracting functions, config from the environment, idempotent writes, and assertions that catch data changes.
Fan-out is the most dangerous bug in analytics because it makes numbers look bigger, not smaller. What grain means, how a join silently changes it, the four ways to fix double counting, and the two checks that catch it in seconds.
Most dbt test suites are green and catch nothing. The four generic tests that earn their place, how to assert your model's grain, writing business-specific tests for reconciliation and freshness, and using severity so people keep paying attention.