Top 25 Power BI Interview Questions & Answers

welcome to kcr data vision youtube channel in this video we are going to see the top 25 questions that are frequently asked in power bi interview now based on the feedback of the students candidates as well as some of the panelists what we have observed is there are few questions which are repetitively asked and we have listed down and we'll be walking you through one by one so that will be the agenda for this video to start with in power bi we do our four main topics one it's the transformation layer one is the presentable layer and one is very important in terms of the calculations dax is our right hand to power bi and we also will be seeing power bi service so we have divided the set of questions into four parts so we will walk you through one by one there is no specific order that will be followed in interview but whatever questions is coming in each part will be the repetitive questions to start with we'll see this power query editor so this is a very important layer in power bi reports because this is where you start cleaning your data start shaping your data doing all the transformations so whenever you get a question like what you have done in your project what was your roles and responsibilities so slowly they start asking about power query editor they'll ask you what are the transformations you have used in your project there are many transformations in power query editor like you have text transformations number transformations date transformations and along with that you have conditional formatting conditional changes conditions you can apply those type of things you can do it in your power query editor so whatever you have worked whether your work joining the tables or you are like appending the data or you're applying some conditions you're replacing the values you're changing the data types all these are called transformations just you can say that i worked on trex transformations number transformations day transformations in power query editor now we all know that power bi supports 99 data sources 99 plus data sources so the frequently asked question is what type of data sources you have used in your project now in the real time maybe you'll be getting the data from your database the database could be a sql server it could be a oracle database it could be a flat files it could be a json files it could be an xml files it could be a folder files so it can come from the share folder so you just need to name around three to four for this second question now whenever you're bringing the data to your power bi you can either bring it in two ways one will be the import mode and one will be the direct query mode understand that power bi is an application it's a app which will have some space where you can store the data it will have some cache data cache space where you can show the data when you're trying to bring the data from different sources and you're storing it in your power bi that becomes an import mode so what is the advantage of import mode is the complete data is in your control you can do whatever you want you can remove add columns you can do whatever the transformations you can write dag functions completely it's in your control the only disadvantage is going with import mode is sometimes the data will be very huge that cannot be brought into power bi that's the only issue for that we have an alternative the alternative is we have something called direct query mode so what is this directory mode direct query mode is you're trying to access the source tables via a query let's say select start from table select star from view you try to access the data by giving a reference in this case what happens the data will not be brought into power bi but only the reference will be called in case if you just go and plot any charts you will not be able to see the data but directly it will go to the source tables maybe it's in a sql server or it's in mysql it will calculate whatever the method you have implemented it will bring only that calculation and it will be implemented in the charts you will not be able to see the data in the direct query mode only this is useful for referencing the date tables from different sources now what is advantage of this since you are not bringing the copy of the data here you can connect any huge data that's the one advantage so as and then it is also having the cons as well the cons is some of the time intelligence function some of the dag functions is not working for direct query mode so either you can go with the import mode or a direct query mode both is having pros and cons just try to understand what is this pros and cons now in the power query editor you also have power pivot which is responsible for creating the model the most asked question is what is the difference between a fact table and a dimension table in every model i can say that there is always a two type of tables and these two type of tables i can say it as one with the complete business data and one is like a lookup data so complete business information i can call it as a fact table and i can say whenever you have a lookup tables for example every country is given is given with the id every customer is given with id those things can be put into one lookup table which acts like a dimension table and now the follow-up question will be what type of schemas you have used so when they ask about the schema you can talk about the star schema or snowflake schema when all the dimension tables is connected to a fact table which can be resembled in shape of a star it becomes the star schema now what is snowflake schema snowflake schema is again a schema where some of the dimension tables can have another dimension table connected to it or a fact table can be connected to a dimension table indirectly this too can be the difference with respect to optimization star schema performs better the joins are simpler but in case of snowflake the joins are bit complex and also optimization if you see it takes huge time now finally one question you can expect is what is the difference between append and merge basically if you want to combine two data sets it's basically applying a join join in sql is equivalent to merge in power bi whereas if you want to append the data one after the other just like a union operation you can go with append so this is all the questions that will be frequently asked in power bi interview in terms of power query editor so if you are aware of this i think most of you will get similar questions and again i'm repeating your presentation is very important the way you present the answer the way i have explained each and every question follow the same way to get better presentation skills now most of the times they ask questions on power view which is basically a normal one okay oh what is your experience in building reports what type of charts you have used so we do have 30 charts in our default 30 plus so we commonly use like column chart pie chart donut chart cards multi cards kpis maps we use waterfall chart we use marketing data if you have you will use funnel chart so this type of commonly used charts will be there rather than explaining just giving the names you try to give an example for example uh i had a situation where i wanted to compare year on year the best chart i used was waterfall chart i had a situation where i wanted to see the marketing strategies i used funnel chart there were some key numbers which i wanted to point it out i've used cards and i've also used multi cards which will give the multiple value explain in this way this will give you a good impression to the panelists the way you approach it and apart from that you can also start speaking if you're not as speaking definitely they will ask you question what are the custom charts you have used so there are around 250 plus custom charts you can go with something like um drill down charts is there instagram is there infographic charts is there then we do have um like comparing between the two categories we have tornado chart is there and we do have san k chart which is used for uh used for comparing categorical with categorical so this type of charts if you can say the panelists will have a good impression that you have worked with the most of the charts and the most widely asked question is what is the difference between filters and slices so filters is something which is within the tool where you will not be knowing what filters has been applied only a developer knows what type of filters has been applied there are three types of filters page level filter visual level filter report level filter if you want to affect only on that visual you will be using visual level filter if you want to have the all the visuals in the page to be affected you will be going with a page level filter whereas if you go with report level filter all the pages the filter will get affected whereas slices it's a very good um factor here what it will do is it will become a user friendly interaction it can be displayed on the screen on the report and it will make every user understandable and they can select it and it will get affected similar functionality but different use case filter can be used only by developers and if anyone who has to use as an end user they can't go and operating the filters they'll not be knowing it instead they can use slices so slices is a very good user friendly interaction a way where you can try to filter out all the records and here also you do have page level filter or page level slicer where you can go with default one if you want to go with all the page if you want to apply this slicer you can go with sync slicer sync slides is the opportunity for you to apply this filter with respect to all the pages and in fact one advantage of going with slicer is you can have selected pages as well you can have selected pages where your slicer has to work but in case of filter that's not possible and also you have edit interaction which basically blocks certain visuals in affecting the slicer so these things if you can put it in a normal simple sentence formation that should be more than enough coming to bookmarks bookmarks is a very important concept nowadays everyone is using bookmarks in all of their projects so what is exactly happening is you try to put some visuals into mark i can say it as you mark certain visuals and you can use it for enhancing the report and next follow-up question is like how do you make your report dynamic by making use of bookmarks by selecting certain visuals and by also making use of buttons and actions you can make your report dynamic you can start making your reports even more dynamic by using these three concepts so this bookmarks buttons and actions becomes a very important factor nowadays all the panelists are asking this questions how do you make your report dynamic so bookmark is um added advantage to power bi it will mark certain visuals into groups now this is about charts so usually most of the times they'll ask you what type of chart you will use what charts you have used in your project so be specific to this and present it in a neat format now this is the most challenging part 50 of your questions will come under dax and power bi service so let's see what is this tax so that's basically an added advantage to your power bi it becomes a right hand to your power bi it solves lot of things by providing calculations you have a lot of functions we have around 250 to 300 functions which will help us to come up with additional information now the first question they'll ask is what is the difference between a measure and a calculated column so measure is a generic function which will not stay on the data set it is just a calculation if you drag out with the any of the visual the generic function will be applied to any of the visual that's the purpose of using measure well coming to the calculated column calculated column is adding a new column to the data set that new column will go and sit in the data set which will utilize your space now there is a purpose where you have to go with measure there is a purpose you have to go with calculated column so based on that you can go with it but the answer as a panelist i will be expecting is the way you use the measure generic function which can be applied to most of the similar visuals and calculated column which is a required column for my business now as i said there are 250 functions available index so the most commonly asked question is what are the functions which are used in project so we do have filter functions time intelligence functions date functions logical functions mathematical functions so all these functions you can pick two or three and talk about it as i said every time try to give an example so in the filter functions you have calculate calculate table all all except all selected maybe you can select two to three in this and explain them coming to time intelligence function the time intelligence function this is a very important set of functions where in most of the reports they'll ask you what was your previous month sales previous year sales and also they may ask you what was last year's sales so for this your time intelligence functions becomes a very important factor here you can solve any type of um calculations and one important point you have to remember is for most of the time intelligence functions it is always better that you create your ma date master date master will be very useful and it will make your calculations easier if you are going with time intelligence so when this question is asked you can say it as i work with filter functions time intelligence functions date functions mathematical functions logical functions pick out one or two from each and explain them with an example this is what as a panelist we will be expecting and one frequently asked question is what is the difference between sum and sum x so both does the same operation but sum is an aggregated calculated column like for example you have um total sales the sales column is that you want to find the total sales value so you can just write sum of sales now what is the condition for applying this the actual column has to exist only then i can apply some function and this sum functions now becomes a generic measure that can be dragged on to any visual now coming to some x some x's even though you don't have the existing column still you can go and apply the calculation row by row by giving an expression that becomes sum x now if they ask this question you need to give an example if there is an existing column of sales i can go and apply some function if there is no existing column of sales still i want to achieve the same functionality i can go and use some x it will be an expression by using any two columns i can write an expression now one more point you need to add is sum x is a row level context whereas sum will be the aggregated value now coming to summarize so summarize is a table level function which will give us a new table as per the requirement if you want to have any group by data country by sales customer by sales and this table or this data could be most repetitive in most of the visuals rather than every time going and jumping into the main table you can create some tables we have a table functions you can use the summarize and you can achieve it basically this function used to summarize the data now all and all except this is also very important this is a filter function whenever you want to use whenever you want to calculate the grand total this two functions will be pretty important so whenever you want to take a filter and if by default if you drag it to any visual the filters context will change if you don't want to change the filter context none of the filters should be affected then you can use all filter and the certain conditions that only one set of column or two set of columns has to be avoided in that case i can go with all except so we also have a video for all and all except uh that we have created you can go through our playlist you will get a clear picture uh that will help you to answer this question now what is the need of date master that had we discussed for most of the time intelligence functions your calculations has to be taken with respect to today's date for example today will be the date and you can take last one month last quarter current quarter current physical year so all this is something which we keep as a reference by creating the date master you are telling the system that this is what is the correct date and based on this today said please calculate so that's the purpose of date master if you are having a lot of time intelligence functions please use this date master as a table now most of the time intelligence functions will be asked the one commonly asked question is same period last year now let me give an example always you cannot compare your current month with the last month example january month you cannot compare with december month december due to vacation due to christmas due to new year maybe the sales are up in january maybe it's a fresh year everyone will not spend money maybe the sales will be down so you cannot compare january with december so what you can do is you can compare the current month current year january with last year january or you can compare this year december with last year december so that gives you the same period last year you can give a use case comparing like what if the sales is behaving every december so this december i'm comparing with the last year december you can give a use case and explain them these are all the frequently asked question in tax now coming to the last part this is also the very important part most offers will fail in this section that's because you may have not implemented it real time so what is this power bi service power base service is responsible for publishing your report to the service and you will see lot of restrictions lot of features there the first question they'll ask you is there are pro premium and normal account they'll ask you what account you've used so the best way is you can you you can say that you have worked with pro account but there are some features which you will be seeing in pro and some features you'll be seeing in premium premium access will not be given to everyone there will be one in a team or a two in a team or even the lead of the team they can hold it and with the premium you can go and schedule the refresh you can create the data flows you can do whatever you want in the premium because that is the highest license you can have it and we do have a normal account as well as a pro account so we will again create a video uh to differentiate it but for now remember this is an important interview question now whenever you're working a simple example i'll give what is the difference between your rough notebook and a class book ralph notebook is something you keep it for a rough hand and notebook or a class book is something which you maintain in a neat format because that is something that will be shown to the many people similarly the difference between the my workspace and the workspaces my workspace is for my personal use only i will be able to see all the reports that has been put into the workspace i will be the only eligible person who can go and see it when i come for the workspace workspace is generically for the entire collaboration of the team multiple people can go and work can go and publish the report into one workspace it's common for everyone for one project you can have one or more workspaces where all the team members will go and work that can be called as workspace whereas my workspace only for me only i'll be able to see the best use cases for my research now in terms of the roles right so we do have a workspace roles like we have admin we have contributor we have member and we have viewer so these are the four roles that you have to know it so admin is a person who can access anything who can add as many as people as they as he likes and he will be having the highest access whereas the lowest access is been given to viewer viewer will be able to see only the view viewing the data he will not even be able to see the data as well and he will not be in the position to add anything now coming to the member on a contributor a contributor is responsible for trying to contribute to the report he will be able to uh he will be able to add features to the reports whereas member is almost having a equal role but he will be one position higher than the contributor he will be able to add other people but not the admin so in this case the rules has been defined try to stick on to a rule where you can explain what exactly happens in each rule now coming to very important question what is rls so this row level security is a very important question that will be asked in almost all the interviews so what exactly we are doing is we are restricting certain records to the users for example if you are in india we restrict your china data if you are from u.s we restrict your india data so like this we restrict your data to a certain report you are not supposed to see other countries if that is a restriction we can usually go with row level security there are two ways you can achieve it one is a static one one is a dynamic one when i say static you can just go to the manage rules and you can set up some filters and you can add the certain people to the certain region and only those people will be able to access it now this is a common one that everyone can do it but only disadvantages you need to manually go and add everyone and also every rls has to go from the desktop to power base service directly in power bi service you cannot do now this is a bit big process so we have something called dynamic rls so this dynamic rls is basically i can say it as we can use user principle name as a dac function which is responsible to capture the system name or username based on that you will be given access to the reports now in this case once you give this you can also have an entitlement table what type of access they need in a separate table you can map it and in the power bi service you can give access so when they ask this question please explain about both static and dynamic if you just go with static maybe they assume that you have just red and game but if you are explaining in a dynamic they will get that confidence that you also worked on dynamic reporting okay now when they ask what is the difference between a report and a dashboard report is basically that you will be like using for your applications a report you can have more than one report you can have even three to four reports coming from the different data source for one project but overall we create a one single dashboard that's the practice we use it many reports will be comprised into one dashboard and we can also put it in this way report is interactive whereas that dashboard is basically like a snapshots which comprises of all the visuals in the tile format properly arranged in a tile format that you can tell so this is very important they may ask you how many reports you add how many dashboards you have built so this is something you can answer it now what is a gateway so usually what is a gateways gateway is responsible for moving your data from on-prem to your services or from connecting your desktop your services you should be having an initial step that is a gateway the gateway is the connectivity mode between your data set as well as the service now there's two ways one is a standard and one is a the normal one personal gateway so personal gateway is basically only one person can use it's for personal use it's for a practice or a research purpose and the standard gateway is usually the preferred one where most of the your colleagues whoever is working for report will be having access to manage it and they'll have all the access to change it now we all know about power query editor which is used for the transformation but the next question is can you do transformation in services this is a question that most of you have yes it's possible and how it is possible you have something called data flows by using the data flows in the power peer services you can create your data sets you can create you can reuse the data set which is already been used by different workspace or different data and also this will help us to transform the data whatever the transformations you were doing it in power query editor can be done in can be done in power bi service as well so what is data flow you can simply say it as power query editor in power ps service whatever the operations you are doing in power creator directly i'm going and do it in power bi service that becomes a data flow so all these questions will be repeatedly asked in almost every interview and you need not answer all the questions seven out of ten eight out of ten should still clear your interview please concentrate on all these questions uh get into the deep of this we have posted many videos on each of the every question try to understand in depth and present it in a good way so these are the top 25 questions that are repetitively asked in every interview please keep an eye and thanks for watching [Music] [Music]

Channel: KSR Datavizon

Views: 222,850

Keywords: power bi interview, power bi interview questions, power bi interview questions and answers, power bi, interview question for power bi developer, power bi developer interview question and answer, power bi interview questions and answers for experienced, power bi interview question, power bi desktop, interview tips, power bi tutorial for beginners, power bi tutorial, how to become a power bi developer, power bi training, KSR Datavizon

Id: WM7RSMzKrZ8

Length: 29min 43sec (1783 seconds)

Published: Wed Feb 02 2022