Exam 70-778 topic 1 question 105 discussion

The answer should be D. I you change the data type of DateID to Date, you would not be able to create a link (relationship) with "ActivityStart" column, since the Activity Start column has a datatype of Datetime.

Why Not Option A?

I tested and will vote C, as: 0.create n-1 relationship between ActivityLog[activityStart] DateTime column and ActivityDate[DateID] Number column 1.create table using "Table = NATURALINNERJOIN(ActivityDate,ActivityLog). " no row showed even there is match record. 2.change ActivityDate[DateID] type to Date 3.verify with table using "Table = NATURALINNERJOIN(ActivityDate,ActivityLog)". It successfully show the row matched. so it looks datetime and date column has no problem to match. but datetime or date column has problem to connect with number column even the format looks similar. if D is changing ActivityLog[activityStart] from Datetime to Date , still doesn't work with number column. is it logical?

In my opinion also C because format function will give you text column type which therefore should be changed to number column in order to create relationship. And column as number or even text in yyyymmdd format can be easily ready by Power BI as date in proper order after changing data type.

I go with C. becoz the only problem here is Dim Date table is a number column, we need to change it into "Date" so that we could use time intelligence function. I will do it in PQ editor, 1st change "number" to "text" and then to "Date", it will work, tested before while I prep for 779.

A. Change the Data Type of ActivityStart to Date --> not needed, is already a date format B. Create a measure in ActivityLog that uses the FORMAT DAX function. --> You want to join tables and therefore you need a column not a measure C. Change the Data Type of DateID to Date ---> will produce an error in Power BI Desktop Data view as well as in Power Query D. Create a calculated column in ActivityLog that uses the FORMAT DAX function. ---> YYYYMMDD = FORMAT(DimDate[FullDateAlternateKey],"yyyymmdd") Now you can join the tables

Actually, one field is a datetime field and the key in the other table is yyyymmdd. Even if you would change the key to a date field, it would still lack the time information. I guess that is what raspberry wanted to say. You would still have no valid connection between the two fields. In either way, you will have to transform the Datetime field to yyyymmdd format. Therfore the only valid answer is D.

The Answer is D: A: If you change date type to date, you will lost time information. (Never do that in the real life). C: Don't use date as a primary key type for any table.

It is C. When you want to transform ISO date (yyyymmdd) into a date, you have to add two steps: first to change date column into text, and then to change it from a text to a date while adding a new step. If it only replace the previous step, it will give an error, so in some versions of Excel you have to type M Code for this second step.

C and D works. More reasonable is to keep Date Type in both columns for time intelligence purposes. I go with C.

I'm going with C

D. That will be this formula: FORMAT( ActivityLog[ActivityStart], "yyyymmdd" ). PowerQuery (M) , this is C, returns error when you try to change value number yyyymmdd to date.

Can someone explain why D is the right one ?