# MDX #23 – “Hello World!” Lesson in MDX

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Almost every tool we learned has some sort of “Hello World!” tutorial lesson.

So here comes the “Hello World!” lesson in MDX.

#### Putting “Hello World!” directly on the X axis doesn’t work

You would think this query would work, by putting “Hello World!” directly on the X axis.

Unfortunately it doesn’t.

#### [Measures].[x] is a perfectly legitimate and unique name for a tuple

The X axis expects a tuple/set expression. Or put it simply that it expects something like this:

[A Dimension].[A Hierarchy].[A Member]

To save some typing, I am going straight to the one special dimension in any SSAS cube, that is, the [Measures] dimension. This special dimension also has only one hierarchy, which happens to have the same name, [Measures]. This save me time to type it twice.

To further save myself typing, I am going to use one letter x for the member.

[Measures].[x] is a perfectly legitimate and unique name for a tuple. It’s a very rare chance that any cube designer would name any of the measures [x].

#### Do not use any existing member

If you try to use a measure that has already existed in the cube to represent “Hello World!”, you will get an error.

#### MDX for arithmetic calculation

If you are like me who writes so much SQL code every day that I never use the Calculator software on my PC for arithmetic calculation. SELECT 9999999 + 1 is a perfectly fine query and will return 10000000.

A bit more typing than in TSQL, but this works in MDX.

Even better, if you want to format it, go ahead use the format_string.

#### We can create a member on any dimension

[Measures] is not the only choice for a perfect “Hello World!” lesson. As a matter of fact, you can use any dimension in the cube, but it requires a bit more typing.

Let’s pick the Date dimension.

#### But don’t forget to pick a hierarchy

It didn’t work, because unlike the special [Measures] dimension, the [Date] has many hierarchies, including a dozen or so attribute hierarchies and a few user-defined hierarchies.

Let’s pick the user-defined hierarchy [Calendar].

If you want to summarize the “Hello World!” tutorial lesson in MDX, go right ahead!

For my other MDX blogs, visit http://bisherryli.wordpress.com/.

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