is it possible to use conditional select ? i want to implement something like that:
if (some_condition)
with ....
select ....
from **cube1**
else
with ...
select ...
from **cube2**
the number of columns may vary depending on cube we are using.
is it possible to make this piece of code work? if yes, how to do this with less blood (i mean with minimal cube amendments)?
Related
In MDX, we can CROSS JOIN two members, a measure and a member but not two measures. Why is this so? What does it imply?
SELECT
[Measures].[xyz] * [DimTable1].[SomeHierarchy].[Level] on 0,
[DimTable2].[SomeOtherHierarchy].&[Value] on 1
FROM [MyCube]
// WORKS
SELECT
[Measures].[xyz] on 0,
[DimTable2].[SomeOtherHierarchy].&[Value] * [DimTable1].[SomeHierarchy].[Level] on 1
FROM [MyCube]
// OF COURSE IT WORKS
SELECT
[Measures].[xyz] * [Measures].[ABC] on 0,
[DimTable1].[SomeHierarchy].&[Value] on 1
FROM [MyCube]
// DOES NOT WORK!!
I believe you forgot:
SELECT
[dd].[hh].[mm1] * [dd].[hh].[mm2] on 0,
[DimTable1].[SomeHierarchy].&[Value] on 1 FROM [MyCube]
did not work neither. [Measures] is not different than [dd] in my example. In MDX you cannot define a tuple with _ several members _ of the _ same hierarchy _. Have a look to this gentle introduction explaining the main concepts.
EDIT
Your third query, that does not work, looks like this:
The yellow area is empty so it is understandable that it is not happy.
EDIT
Following is an analogy using Excel pivot tables which use OLAP technology
If you put a crossjoin of measures A and B on rows you get something like this:
Then if we add a very small level (with 4 members) onto columns we get the following:
So what will go into the main body of this table?
A count is possible and probably is, in MDX, if you create a custom measure (don't have a server to test this statement on). Excel will default to a count but the result is pretty pointless?
I was always bothered by how should I approach those, which solution is better. I guess the sample code should explain it better.
Lets imagine we have a table that has 3 columns:
(int)Id
(nvarchar)Name
(int)Value
I want to get the basic columns plus a number of calculations on the Value column, but with each of the calculation being based on a previous one, In other words something like this:
SELECT
*,
Value + 10 AS NewValue1,
Value / NewValue1 AS SomeOtherValue,
(Value + NewValue1 + SomeOtherValue) / 10 AS YetAnotherValue
FROM
MyTable
WHERE
Name LIKE "A%"
Obviously this will not work. NewValue1, SomeOtherValue and YetAnotherValue are on the same level in the query so they can't refer to each other in the calculations.
I know of two ways to write queries that will give me the desired result. The first one involves repeating the calculations.
SELECT
*,
Value + 10 AS NewValue1,
Value / (Value + 10) AS SomeOtherValue,
(Value + (Value + 10) + (Value / (Value + 10))) / 10 AS YetAnotherValue
FROM
MyTable
WHERE
Name LIKE "A%"
The other one involves constructing a multilevel query like this:
SELECT
t2.*,
(t2.Value + t2.NewValue1 + t2.SomeOtherValue) / 10 AS YetAnotherValue
FROM
(
SELECT
t1.*,
t1.Value / t1.NewValue1 AS SomeOtherValue
FROM
(
SELECT
*,
Value + 10 AS NewValue1
FROM
MyTable
WHERE
Name LIKE "A%"
) t1
) t2
But which one is the right way to approach the problem or simply "better"?
P.S. Yes, I know that "better" or even "good" solution isn't always the same thing in SQL and will depend on many factors.
I have tired a number of different combination of calculations in both variants. They always produced the same execution plan, so it could be assumed that there is no difference in the performance aspect. From the code usability perspective the first approach i obviously better as the code is more readable and compact.
There is no "right" way to write such queries. SQL Server, as with most databases (MySQL being a notable exception), does not create intermediate tables for each subquery. Instead, it optimizes the query as a whole and often moves all the calculations for the expressions into a single processing node.
The reason that column aliases cannot be re-used at the same level goes to the ANSI standard definition. In particular, nothing in the standard specifies the order of evaluation for the individual expressions. Without knowing the order, SQL cannot guarantee that the variable is defined before evaluated.
I often write multi-level queries -- either using subqueries or CTEs -- to make queries more readable and more maintainable. But then again, I will also copy logic from one variable to the other because it is expedient. In my opinion, this is something that the writer of the query needs to decide on, taking into account whether the query is part of the code for a system that needs to be maintained, local coding standards, whether the query is likely to be modified, and similar considerations.
I've just started to learn MDX and i want to do a query like that:
filter data by the cost ( i've already made that query but without the sum) like that:
SELECT [Measures].[SumOfSelled] ON 0,
FILTER ([From].[From].[City].members, [Measures].[SumOfSelled]>7000) ON 1
FROM [BI-Avia]
It's working
and it is OK
BUT!!!
I need also to show the sum of filtered elements under this filtered result by cities
I know how to find it separately:
with member [Measures].FilteredSum as sum(filter([From].From].City].members,Measures].SunOfSelled]>7000),Measures].[SumOfSelled])
select{SumOfSelled} on 0
from [BI-AVIA]
But i have to show this together!! The SUM under Filtered! two in one! I need youe help! I think it's very clear for you!!!
Just define the calculated member on the [From].[From] hierarchy and then combine both queries, using a union of sets (abbreviated with + in MDX):
with member [From].[From].FilteredSum as
sum(filter([From].[From].City].members, Measures].SumOfSelled]>7000))
SELECT [Measures].[SumOfSelled]
ON 0,
FILTER ([From].[From].[City].members, [Measures].[SumOfSelled]>7000)
+
{ [From].[From].FilteredSum }
ON 1
FROM [BI-Avia]
You could possibly define the filter as a set in the WITH clause, which would avoid that Analysis Services evaluates it twice.
Can someone please remind me how I do this?
I want an MDX query (MS SSAS) which will query a dimension. Not interested in cubes or measures.
So far as I remember the syntax involves a $ sign, something like [$MyDimension].
I know I can do the below, but I want to query the dimension without touching a cube.
select [DimensionName].Children on 0 from [CubeName]
I guess they're called "dimension cube":
select [dim].members on 0 from [$dim]
or
select [Measures].defaultMember on 0, [dim].members on 1 from [$dim]
I am on a work term from school. I am not very comfortable using SQL, I am trying to get a hold of it....
My supervisor gave me a task for a user in which I need to take row data and make columns. We used the Crosstab Wizard and automagically created the SQL to get what we needed.
Basically, we have a table like this:
ReqNumber Year FilledFlag(is a checkbox) FilledBy
1 2012 (notchecked) ITSchoolBoy
1 2012 (checked) GradStudent
1 2012 (notchecked) HighSchooler
2 etc, etc.
What the user would like is to have a listing of all of the req numbers and what is checked
Our automatic pivot code gives us all of the FilledBy options (there are 9 in total) as column headings, and groups it all by reqnumber.
How can you do this without the pivot? I would like to wrap my head around this. Nearest I can find is something like:
SELECT
SUM(IIF(FilledBy = 'ITSchoolboy',1,0) as ITSchoolboy,
SUM(IIF(FilledBy = 'GradStudent',1,0) as GradStudent, etc.
FROM myTable
Could anyone help explain this to me? Point me in the direction of a guide? I've been searching for the better part of a day now, and even though I am a student, I don't think this will be smiled upon for too long. But I would really like to know!
I think your boss' suggestion could work if you GROUP BY ReqNumber.
SELECT
ReqNumber,
SUM(IIF(FilledBy = 'ITSchoolboy',1,0) as ITSchoolboy,
SUM(IIF(FilledBy = 'GradStudent',1,0) as GradStudent,
etc.
FROM myTable
GROUP BY ReqNumber;
A different approach would be to JOIN multiple subqueries. This example pulls in 2 of your categories. If you need to extend it to 9 categories, you would have a whole lot of joining going on.
SELECT
itsb.ReqNumber,
itsb.ITSchoolboy,
grad.GradStudent
FROM
(
SELECT
ReqNumber,
FilledFlag AS ITSchoolboy
FROM myTable
WHERE FilledBy = "ITSchoolboy"
) AS itsb
INNER JOIN
(
SELECT
ReqNumber,
FilledFlag AS GradStudent
FROM myTable
WHERE FilledBy = "GradStudent"
) AS grad
ON itsb.ReqNumber = grad.ReqNumber
Please notice I'm not suggesting you should use this approach. However, since you asked about alternatives to your pivot approach (which works) ... this is one. Stay tuned in case someone else offers a simpler alternative. :-)