What is MDX?

According to Wikipedia MDX stands for MultiDimensional eXpressions. It’s a SQL dialect to access OLAP cubes.

So what’s different to “normal” SQL? Basically you don’t have any tables or views, you just have a collection of fact and dimensions.

A fact is the recording of the occurrence of an event: “On July 28th 2014, mrs Jones from 4 Sally Nogging Road, Dun Loaghaire, Ireland, at 10:21 am bought 4 pounds of Ben and Jerry Cooky Dough Ice Cream at mr. Humpries Butcher shop, she was helped by a store clerk called Maria etc… etc…”

A dimension is the description and categorisation of an element related to the fact.”mr. Humpries Butcher shop is owned by mrs. o’Conner, it’s a COOP franchise, it’s located at 12 Dublin Street, Dun Loaghaire, County Dublin, Ireland etc… etc…”

MDX allows you to organize these facts and dimensions in columns and rows.

Is MDX hard to learn? If you have a basic understanding of SQL, MDX is not hard to learn. The mean difference is that you have to start to think in more than two dimensions, but we will get to that later.

For the time being I will do all my posts on this blog against the SSAS 2014 demo cube “Adventure Works”.

Till Next Time.