SQL Server Query Fundamentals: A Simple example of a Query that uses PIVOT:

Problem:

Convert the following source data into a schema shown below:

SQL SERVER TSQL PIVOTSolution:

Here’s the code that uses PIVOT function to get to the solution, please use this as a starting point.

Note the use of aggregation function avg – this will depend on the requirement. In the example, the Test_value need to be average if more than one tests were performed.


-- source data
SELECT [Product_ID],[Test_Desc],[Test_Val] FROM [dbo].[Address]
go

-- Destination data using PIVOT function
select * from [dbo].[Address]
pivot( avg(test_val) for test_Desc IN (Test1,Test2,Test3,Test4,Test5)) 
as Tests

TSQL – Quick note about numeric data type to solve “Arithmetic overflow error”

Problem:

You are working on a query where you are trying to convert source data to numeric data type and you get an “Arithmetic overflow error”.

Solution:

Let’s understand this with an example:

Here’s the source data: 132.56000000 and you want to store just 132.56 so write a query that looks like:

cast( as numeric(3,2)) as destination_column_name

and after you run the query its throws an error “Arithmetic Overflow Error” – so what’s wrong?

The issue is that you incorrectly specified the precision and scale – by writing the query that says numeric(3,2) you are saying I want 3 data places with 2 on the right (after decimal point) which leaves just 1 place for left.

what you need to write is numeric(5,2) – and this will have 2 places on the right and leaves 3 places for left.

so after you run this, it shouldn’t complain about the arithmetic overflow error. you just need to make sure that the precision and scale of the numeric data type is correct.

Conclusion:

In this post, you saw an example of how to correctly use the precision and scale in the numeric data type and that should help you solve the arithmetic overflow errors.

SQL Server Analysis Services (SSAS) multidimensional cube: How to create a role playing dimension?

Summary:

I was recently asked by a SSAS developer about how to set up a role-playing dimension so I did a brief demo to show how to set it up. In this post, I am document the steps to help you get started:

What is role-playing dimension?

What if you want to see sales data by Order Date as well as Shipped Date? You can one date dimension that is used more than once for seeing sales data by order date and shipped date. In this case, date dimension becomes a Role Playing Dimension.

Steps:

1. Open SQL Server Data Tools and SSAS project that you are working on.

2. Go to Data Source Views from the solution explorer.

3. Make sure that the relationships are specified between dimension (e.g. date dimension) and Fact Table (e.g. Fact Sales). Example: If you’ve OrderDateSK and ShippedDateSK in your fact table, then establish a relationship between the both columns with the Primary Key of the Date dimension.

SSAS Data Source View Role playing dimension

Note: If you do not have the relationships specified in the data source views, there’s an alternative to go to dimension usage for a cube and setup role playing dimensions. since this is targeted to get you started, I am not covering the steps for that.

4. Now go to the Dimensions section in the solution explorer and add a Dimension that uses the existing data source view from step #3.

5. switch to Cubes.

Now, if you don’t have a cube created yet then you can use the cube wizard if you want and as long as you have the relationships specified at DSV’s, it should create a role-playing dimension.

Alternatively, you can also create a new dimension. In the Design pane, lower left section, you’ll see dimensions.

Add Dimensions Cube SSAS

select your dimension that you created in step #4 that’s a role-playing dimension from the list and click on OK. And it creates a role-playing dimension for you! So all you had to do was to make sure the relationships are created between the fact and (role-playing) dimension table and SSAS does the rest of the work for you

SSAS Role Playing Dimension

 

Note: for the demo I didin’t rename the dimension attributes but you do all that good stuff too when you are building the cube for users!

Conclusion:

In this post you got started on how to add a role-playing dimension in a SSAS cube.

SSAS Multidimensional cube: How to solve duplicate attribute key error when attribute is non key?

Problem:

In SSAS multidimensional cube, while processing a cube, you get an error/warning for a non-key “price” column that says:

Errors in the OLAP storage engine: A duplicate attribute key has been found when processing: Table: ‘Table Name’, Column: ‘Price’, Value: ’29’. The attribute is ‘Price’.

You see, if it would complain about a key column having duplicate attribute that would have been fine but it’s complaining about duplicate attribute key when an attribute is non key. How do you solve this?

Solution:

mostly this is because that the view/table that you are using in your data source views have blanks/nulls.

so in your source, use ISNULL/COALESCE TSQL function before bringing data in the cube OR if it makes sense for you then you can filter out blank data too.

I hope that helps.

SQL Server Reporting Services: How to Solve Divide by Zero Errors?

Problem:

you thought you wrote an if condition to handle “divide by zero” errors in SSRS but still get the run time error?

Example. my expression is:

=IIF(Fields!denominator.Value=0,0,
CINT(Fields!numerator.Value/Fields!denominator.Value))

And I still get the error:
Divide by Zero Error SSRS

Note: if you do not have integers to divide and you allow data conversion to double, it would show on SSRS as “infinity” instead of “#Error”.

Solution:

Let’s understand why does it do it?

So even though you are using IIF condition, the vb IIF condition evaluates every function in every expression before it renders and that’s why the “False” condition that I have in my condition gets run which results in #Error.

Ok, armed with that knowledge, let’s solve the problem.

So here’s a modified version of the expression, have a look:

See what we did there! We added one more IIF condition in the “false” condition of the parent IIF.

=IIF(Fields!denominator.Value=0,0,
CINT(Fields!numerator.Value
/IIF(Fields!denominator.Value<>0,Fields!denominator.Value,1)))

That should solve the problem:
Divide by zero fix customer code ssrs

There’s also an alternative to this especially if you have a lot of expressions that does this. You can write your custom code and call it SSRSDIVIDE or you can come up with a better name! Here’s a post that talks about how to do that: http://salvoz.com/blog/2011/11/25/ssrs-checking-for-divide-by-zero-using-custom-code/

Conclusion:
In this post, we saw how to solve the divide by zero errors in SSRS.

SQL server Integration services: How to solve “The value violated the integrity constraints for the column” error?

problem:

you are working on an SSIS package to load a table from a source system and you get an error “The value violated the integrity constraints for the column error” – how do you solve it?

solution:

one the things that the error message should also tell you would be column name. What you want to do is check the table definition of the destination table for any integrity constraints like NOT NULL or PRIMARY KEY. Now once you have that information, go back to your source and figure out if it’s trying to add NULL values in a column that has NOT NULL integrity constraint. Or may be ETL logic is trying to insert duplicate value to the column that has primary key constraint.

Also, the don’t alter the destination table to accept NULL’s or remove integrity constraint. You want to put a logic in your ETL OR fix the data integrity at source. You can use TSQL functions like NULLIF to handle NULL values while querying source systems.

Conclusion:
In this post, we saw how to solve the “The value violated the integrity constraints for the column” error in SSIS.

SQL server analysis services MDX: Current Fiscal Period vs Previous year same Fiscal Period Query

Problem:

Comparing data current fiscal period vs previous year same fiscal period query is a very common problem. Here’s a sample query.

Solution:

Please use the query as a staring point for current fiscal period vs previous year same fiscal period. I used the Contoso Cube to come with the query. The key part is to use the PARALLELPERIOD function.


with member [Sales Amount Previous Year Fiscal Month] as
SUM(ParallelPeriod([Date].[Fiscal Month].[Fiscal Month],12,[Date].[Fiscal Month].CurrentMember ),[Measures].[Sales Amount] )

select
{[Measures].[Sales Amount],[Sales Amount Previous Year Fiscal Month]} on 0,
NON EMPTY {[Date].[Fiscal Month].[Fiscal Month]} on 1
from
[Sales]

where
[Date].[Fiscal Year].&[2008]

MDX current year vs previous year same fiscal periodConclusion:
In this post, I shared a MDX query that you can use for current fiscal period vs previous year same fiscal period.

SQL Server Integration services: How to write a package that does Set based updates?

Problem:

if you’ve a sizable number of rows that need update in SSIS, then you don’t want to do a row based update commands because it won’t be efficient. if you’ve good number of rows that need to be updated then you can use the SET Based updates. it’s a common design pattern for loading dimensions in a data warehouse.

Find the steps below:

Solution:

There are two main steps to achieve this:

1) Populate the “update” table with rows that have been changed. Note that a new table needs to be created.

2) Run the SQL command to do a SET based update

1. SSIS Set based Updates Integration ServicesLet’s see each step in detail:

1)  Populate the “update” table with rows that have changed.

For this step, first make sure that you have a table that can hold the rows that have been updated.

Then create a Data Flow that take the source data and lookups the data that has changed and puts it in an update/staging table:

2 SSIS Populate the Table with Rows that changed

Note: I’ve used a small table for demo purpose but you won’t use this method if you don’t have a more rows to update because as you can see this method adds an overhead of putting the data in the update table first.

2) Run the SQL command to do a SET based update

Here’s the sample query:

-- run the update command
Update Dim
Set
    [Column1]=Upd.[Column1]
    [Column2]=Upd.[Column2]
--  [Column3]=Upd.[Column3]	
--  ... 
From dbo.DimDestination Dim
Inner Join dbo.Destination_update Upd
on Dim.Destination_sk=Upd.Destination_sk
  
--Truncate update table
Truncate table dbo.Destination_update

Conclusion:

In this post, we saw how to write a package in SSIS that does SET based updates.

SQL Server reporting services: How to use the Split function in the SSRS expressions to get sub-string?

Problem Statement:
How do you use SQL Server Reporting Services (SSRS) expression to get sub-string from the inputted text?

Solution:
I am going to show you few SSRS expressions that you can use in your SSRS reports:

SSRS SQL Server Reporting Services Expression SPLIT

Here’s the same in a text:

Input: SSRS Expression used: Output:
[Date].[Fiscal Year].&[2008] Split(Parameters!DateFiscalYear.Value,”&”)(1) [2008]
[Date].[Fiscal Year].&[2008] Split(Parameters!DateFiscalYear.Value, “.”)(2) &[2008]
[Date].[Fiscal Year].&[2008] Split(Split(Split(Parameters!DateFiscalYear.Value, “&”)(1),”[")(1),"]“)(0) 2008
[Date].[Fiscal Year].&[2008] Parameters!DateFiscalYear.Value.Split(“&”)(1) [2008]

Conclusion:
In this post, you saw how to use the split function in SQL Server Reporting Services (SSRS) expressions to get a sub-string.

SQL Server Analysis services MDX: How to write a query that works as LIKE operator in SQL?

Problem Statement:

In MDX, How to search for a sub-string using something similar to LIKE operator in SQL?

Solution:

here’s an example using Contoso Sales Cube, please use this to get started for your scenario:

Note the use of INSTR function.


select
[Measures].[Sales Amount]
on 0,
Filter(
[Geography].[Region Country Name].[Region Country Name]
,instr([Geography].[Region Country Name].CURRENTMEMBER.MEMBER_CAPTION,'United')>0)
on 1
from
[Sales]

SSAS MDX analysis services like SQL

Also,
if you are looking for NOT LIKE then replace >0 with =0 and you should get the desired results.

Conclusion:
In this post, you saw how to write a MDX query that does sub-string search for you similar to LIKE and NOT LIKE operators in SQL.