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29 lines
2.2 KiB
Markdown
29 lines
2.2 KiB
Markdown
Creating calculated columns is a simple way to enrich and enhance your data. A **calculated column** is a new column that you create by defining a calculation that transforms or combines two or more elements of existing data. For example, you can create a new column by combining two columns into one.
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One useful reason for creating a calculated column is to establish a relationship between tables, when no unique fields exist that can be used to establish a relationship. The lack of a relationship becomes apparent when you create a simple table visual in Power BI Desktop, and you get the same value for all entries, yet you know the underlying data is different.
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To create a relationship with unique fields in data, you can, for example, create a new calculated column for "Full Phone Number" by combining the values from the "Area Code" and "Local Number" columns when those values exist in your data. Calculated columns are a useful tool for quickly creating models and visualizations.
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To create a calculated column, select the **Data view** in Power BI Desktop from the left side of the report canvas.
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From the Modeling tab, select **New Column**. This will enable the formula bar where you can enter calculations using DAX (Data Analysis Expressions) language. DAX is a powerful formula language, also found in Excel, that lets you build robust calculations. As you type a formula, Power BI Desktop displays matching formulas or data elements to assist and accelerate the creation of your formula.
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The Power BI formula bar will suggest specific DAX functions and related data columns as you enter your expression.
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Once the calculated columns are created in each table, they can be used as a unique key to establish a relationship between them. Going to **Relationship** view, you can then drag the field from one table to the other to create the relationship.
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Returning to **Report** view, you now see a different value for each district.
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There are all sorts of other things you can do by creating calculated columns, too.
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