Recently I delivered a session at local conference organized by Microsoft Croatia – WinDays¹º. The title of the presentation was: “DAX vs MDX vs T-SQL”.
As its name suggests, the presentation is oriented towards SQL and BI developers (for change) instead of Excel power-users and compares DAX calculations with T-SQL and MDX expressions. The idea behind, besides improving my T-SQL skills and learning DAX, was to build a mental model of what DAX functions and their combinations actually do by finding their best analogies in other languages. Since there are more than a hundred DAX functions, I’ve concentrated primarily on those that use relations. On one hand, they are probably the most difficult group of functions in DAX. On another, they should be the closest to SQL and BI developers’ mindset.
If you’re wondering why T-SQL and MDX, the reason is simple. PowerPivot uses in-memory column-oriented relational database technology and was developed by SSAS team (together with Excel team). “Relational” means we have every reason to compare DAX with T-SQL. And since SSAS team was involved, MDX comes naturally. Hereby I wish to emphasize that the comparison shown in the presentation was based on imaginary or potential analogies in T-SQL and MDX and not the real implementations built into PowerPivot engine. In the same manner, the summary highlights showing strengths and weaknesses of each language is based on personal impressions. Regardless of that, I believe the presentation might be of great help for many.
The presentation (translated in English) is published on my blog including all the related files. You can find it here.
Looking forward to your feedback.