Power BI | Data sources exercise | Relationships between tables

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Software ==> Power BI  (111 exercises)
Version ==> Latest update
Topic ==> Data sources  (2 exercises)
Level ==> Relatively easy
Subject ==> Power BI training
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Import the Events, Category and Country tables from the WorldEvents.xlsx file, found in the above folder. Look in Relationship View to see what has happened.

No relationships

Annoyingly, no relationships have been created between the tables. There are two ways we can handle this.

The first method is longer but gives a greater level of control. On the home tab of the tool bar find Manage Relationships.

Manage relationships

If only it was as easy as clicking one button....in this case it is! Choose New...

 

This will create a window where there are two drop downs.  From these select the two tables you want to join together. It doesn't matter the order in which you choose them.

Creating relationship

Click on a column from each table to create a join. In this case each event has a corresponding country. EventCountryID and CountryID pair up!

First relationship done! The other way to create one is to click and drag from one column to the other. Try dragging the CategoryID to the EventCategoryID.

Dragging relationship

Thankfully most of the time the names of columns make it clear what the overlap is. Modern databases have a tendency to even use the exact same column name.

The danger of this method is if you miss. To check which columns have been joined let your mouse hover over the line you have just created. Power BI will highlight the two joined columns:

Selected relationship

The 1 means that CategoryID only has unique values while the * means EventCategoryID has duplicates (ie more than one event can be in the same category).

How daft, there was another table we wanted from that excel document! Not to worry - there is a shortcut to reconnect to the file. Find Recent Sources on the home tab.

Recent sources

Connect to previous sources quickly without the hassle of all the browsing!

Bring in the Continent table - this should automatically create a join too:

Auto-created relationship

A relationship has been auto created since they have the same field names, data types and one is unique. Excellent!

Optionally save this as Creating cultural connections.pbix and close it down.

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