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Jeet Kainth

My experience in obtaining an MCSE

Background

I have recently completed my MCSE in Data Management and Analytics, and I wanted to share my experience of working towards and passing the exams that have led to me getting this MCSE. In this post I will cover some of the challenges I faced and provide some tips and advice, hopefully others following the same certification path, or other paths, will find this useful.

I am a business intelligence developer at Purple Frog, I have several years of experience working with data, I started off as a data analyst and then went into reporting and more recently have been working on ETLs, data warehousing and cubes. I have been working with SQL throughout my various roles and therefore the best place for me to start my certification path was with the exam 70-761: Querying Data with Transact-SQL. The path I’ve taken up to this point is:

MCSA: SQL 2016 Database Development
– 70-761: Querying Data with Transact-SQL
– 70-762: Developing SQL Databases

MCSE: Data Management & Analytics
– 70-767: Implementing a SQL Data Warehouse (from the Elective Exam Pool)

The learning material

Although the first exam (70-761) fitted in quite well with my SQL background (I probably knew about 75% of the material beforehand), there was still some work required for me to get to the stage where I felt I was confident in passing the exam. For me, the best resource and my primary resource for learning the material has been the Exam Ref books, so for example “Exam Ref 70-761 Querying Data with Transact-SQL”. These books are structured in a way that the content is split into the sections covered by the exam, for example the books contain a chapter for every skill covered in the exam.

The one downside to the Exam Ref books is that at times it can feel quite wordy if you’re relying on the book alone, so what I found really useful was to supplement this with videos and demos on the topics where I needed a greater understanding. In addition to this, practice and doing exercises helped me to further understand the different concepts as I was able to try what I had learnt and see where I was going wrong.

The final resource that I found useful was Microsoft Docs (https://docs.microsoft.com/en-us/), this is a really good reference point for key facts, for example I found the page on CDC really useful for my latest exam (70-767).

The exam

There are the obvious tips such as sleep early the night before, get to the exam centre with time to spare and so on, but I wanted to share some of the exam techniques I found useful while doing these exams.

My top tip is check that you have covered off and are comfortable with all the skills measured in the exam, the skills measured for each exam can be found in the “Browse Certifications and Exams” section on the Microsoft Learning website (example shown below for exam 70-761). The skills are also stated in the Exam Ref books and as mentioned before the chapters in the book are based on the skills measured in the exam.

This was taken from https://docs.microsoft.com/en-us/learn/certifications/exams/70-761

What’s useful about the skills measured shown above is that it shows the weight of questions per skill in the exam. This is useful because you can work out if you need to focus on a weaker area if that area is a big part of the exam.

Time shouldn’t be an issue in the exam if you’ve prepared well, however some questions are not worded in the best way and can catch you out so do take the time to read each question properly, and do keep an eye on the time remaining after every 5-10 questions.

You have the option to flag questions and review them again later (note some questions cannot be flagged), make use of these flags for questions you are unsure of. This can be particularly useful if you’ve flagged a question and then a later question gives you a clue or reminds you of the answer for the question flagged earlier. Alternatively, you should be provided with a pen and wipeable board where you can make notes so note down the question number and topic so that you can come back to it later.

Next steps

I am currently studying towards the exam 70-768: Developing SQL Data Models, this will help develop my understanding and knowledge of data modelling and working with cubes and will also help me get the certification for MCSA: SQL 2016 BI Development. With these current certifications being retired in the near future the next plan is to work towards the certification Microsoft Certified: Azure Data Engineer Associate.

I hope you have found this blog useful and that you can use some of the tips mentioned in your study plans, all the best!

SSAS Tabular Calculation Groups – avoid using SELECTEDMEASURE or ISSELECTEDMEASURE

Introduction:

There is a very serious limitation in the behaviour of calculation groups when using the SELECTEDMEASURE or ISSELECTEDMEASURE functions, and we recommend not using them. Why? If a user creates their own custom calculations within their Power BI report (or composite model) then the value of SELECTEDMEASURE changes, breaking your calculation group logic.

Let me explain with an example:

In a tabular cube we may look to use calculation groups to apply additional filters when calculating measures. In our example we will be using a retail scenario, with budgets as well as ‘Like for Like’ (LFL) budgets. For those not in retail, LFL represents stores that were also open this time last year. We start with the measure “Budget” with the following definition:

We also have a hidden measure called “Budget LFL” with the following definition:

The measure “Budget LFL” is a variation of the “Budget” measure with additional filters applied at source. We also have a calculation group called “LFL Filter”, this is used to return the hidden “Budget LFL” measure based on the option selected in this filter and has the following definition:

This functionality is demonstrated below where the two visuals from Power BI show the same measure with and without the LFL Filter applied:

No LFL filter applied
LFL filter applied

Problem:

A problem arises when you try to create a custom measure (in the cube or within a Power BI report) and filter by the calculation group, for example we create a measure called “CustomBudget” which is a copy of the “Budget” measure and has the definition:

Adding this custom measure to the visual shown earlier we can see that the calculation group “LFL Filter” has no affect on the custom measure:

LFL filter applied

This is because the SELECTEDMEASURE() is now [CustomBudget] and not [Budget], therefore the logic in the calculation group doesn’t recognise the selected measure, and therefore doesn’t switch to the LFL measure.

Workaround:

To get around this we move the bulk of the logic from the calculation group to the measure itself. The measure now changes its behaviour by looking at the selected value of the LFL filter, instead of the calculation group managing it centrally:

This is the new definition for the “Budget” measure
This is the new definition for the “LFL Filter” calculation group

We refresh Power BI and find that the results are now as expected, the original and custom measures now match when using the calculation group as a filter:

This is the same visual but using the new logic, now with matching results

Thank you to Darren Gosbell (Twitter | Blog) for the suggestion of this workaround.

Cube deployment error: Cannot resolve all paths while de-serializing Database

I recently came across the following error while deploying a tabular cube using the Analysis Services Deployment Wizard:

My updates for this deployment included removing a table from the cube. As part of the cube deployment options I chose to “Retain roles and members”. However the issue here was that an existing role was referencing the table I had deleted, for example the below image shows the Role Manager in Visual Studio and shows that the Cube_Finance role references the “Transaction Type” table.

To resolve this error I simply had to deploy the cube using the option “Deploy roles and retain members”:

This resulted in a successful deployment with the role updated to exclude any references to the deleted table:

Note this error can also occur if a table has been renamed, for the same reason explained above where a role references the “old” table name. The solution is the same: deploy roles and retain members.

SQL LAST_VALUE() wrong results

You may have come across the following scenario when using the LAST_VALUE() function.

You want to find the first or last value loaded in a result set, therefore you use the FIRST_VALUE() and LAST_VALUE() functions like below:

You expect to get “A” for every record in the FirstValue column and “E” for every record in the LastValue column.
However you see the following output:

LAST_VALUE() on its own is implemented from the current row going back to the first row, for example:

  • Row 1 – The only value in scope is A.
    Hence, FIRST_VALUE() & LAST_VALUE() both return A.
  • Row 2 – The values now in scope are A & B.
    Hence, FIRST_VALUE() returns A and LAST_VALUE() returns B.
  • Row 3 – The values now in scope are A, B, C.
    Hence, FIRST_VALUE() returns A and LAST_VALUE() returns C.
  • And so on…

To return the actual last value, add the additional clause ROWS BETWEEN UNBOUNDED PRECEDING AND UNBOUNDED FOLLOWING. This ensures that for each row the LAST_VALUE() function looks at all rows; from the very first row to the very last row. Now, you have the following code (the original code with an extra column using the additional clause):

This gives you the following output, LastValue2 shows the true last value for the result set:

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The Frog Blog

Team Purple Frog specialise in designing and implementing Microsoft Data Analytics solutions, including Data Warehouses, Cubes, SQL Server, SSIS, ADF, SSAS, Power BI, MDX, DAX, Machine Learning and more.

This is a collection of thoughts, ramblings and ideas that we think would be useful to share.

Authors:

Alex Whittles
(MVP)
Reiss McSporran
Jeet Kainth
Jon Fletcher
Nick Edwards
Liam McGrath

Data Platform MVP

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