Microsoft Power BI Desktop is a free Windows application for turning business data into interactive reports. It brings data preparation, related-table modeling and visual report design into one application, so the calculations behind a chart can draw on more than a single worksheet or source.
Connecting Power BI Desktop to data
Power BI Desktop connects to Excel workbooks, text files, databases such as SQL Server, web tables and online services. A connection’s Navigator lets you select the available tables or sheets and preview their contents. You can load the selected data or open it in Power Query for preparation first.
The connection mode determines where reporting data lives. Import loads the selected records into the model, and a refresh is needed to bring in subsequent source changes. For sources that support DirectQuery, data stays at the source and report visuals send queries when needed. That mode depends on the source and network responding to those requests, and it limits transformations to operations the source can process.
Power Query
Power Query Editor records preparation as a sequence of steps. You can remove unwanted columns, filter rows, split a column, replace values and assign data types before loading the result. Converting a text field to a number, for example, makes it available for numeric calculations rather than leaving it as a label.
The Applied Steps list keeps that preparation separate from the original data. Selecting an earlier step previews the table at that point; removing or rearranging steps changes how the query produces its result. The Advanced Editor exposes the query’s M code when the visual commands do not express the transformation you need.
Queries can also merge information from separate tables. You choose the matching columns and join type, then select which fields from the matched table to expand into the result. This creates a prepared table for analysis, distinct from leaving tables separate and connecting them through model relationships.
Model relationships
Model view displays tables and the relationships between their columns. Those relationships determine how a selection in one table restricts records in another. A product category can therefore filter related transaction rows while the category details and transactions remain in separate tables.
Power BI Desktop lets you control relationship cardinality and filter direction. In a one-to-many relationship, the column on the one side must contain unique values, while matching values may repeat on the many side. The diagram shows these distinctions, making the model’s filtering paths visible before they are used by report visuals.
DAX measures
Measures define calculations that respond to the current report selection. Basic summaries include sums, counts and averages; custom measures use Data Analysis Expressions, or DAX, to express calculations across the model. A measure placed in several visuals can return different results for each visual’s categories and filters while retaining the same calculation definition.
Named measures appear alongside the model’s fields and can be added to charts and tables. Quick measures offer dialog-based choices for common calculations and generate DAX that you can inspect.
Interactive reports
The report canvas arranges charts, maps and tables across multiple pages. Fields assigned to roles such as axis, legend and values determine what each visual displays; changing the visual type changes how those fields are presented.
Selections can cross-filter or cross-highlight other visuals on a page. The author controls whether a particular visual filters another, highlights its relevant portion or leaves it unaffected. Visuals that support drilling can also move through levels of detail, with an option to apply the drill selection across the page.
Sharing through the Power BI service
Power BI Desktop saves work locally as a PBIX file. Publishing sends a report and its semantic model to a workspace in the Power BI service, where online access and scheduled refresh are managed. Sources within an organization’s network may require a data gateway for service access.
Desktop authoring is free, while collaboration through the service depends on licenses and workspace capacity. Power BI Pro supports publishing and sharing, and Premium Per User adds further service capabilities. Qualifying Premium or Fabric capacity can let recipients view shared content without a paid per-user license, so the audience’s access depends on where the report is hosted as well as the author’s license.
