Power Query is a data transformation and data preparation tool that is integrated into Microsoft Power BI, as well as other Microsoft products like Excel and Azure Data Factory. Power Query is used to connect, shape, and transform data from various sources before it's loaded into Power BI for analysis and visualization. It helps you clean, combine, and reshape data from different sources into a format that is suitable for analysis and reporting.
Here are some key functions and features of Power Query within Power BI:
- Data Source Connectivity: Power Query allows you to connect to a wide range of data sources, including databases, spreadsheets, web services, APIs, and more. It provides a simple and consistent interface to retrieve data from these sources.
- Data Transformation: You can perform various data transformation tasks within Power Query. This includes tasks like filtering, sorting, grouping, pivoting, unpivoting, merging, and appending data tables. These transformations help you prepare the data for analysis.
- Data Cleaning: Power Query enables you to clean and reshape messy or inconsistent data. You can remove duplicate rows, handle missing values, and apply formatting changes to ensure data quality.
- Data Modeling: You can define relationships between different tables within Power Query, which sets the foundation for creating a data model in Power BI. This is essential for building accurate and meaningful visualizations.
- Formula Language: Power Query uses a formula language called "M" for expressing data transformations. This language allows you to write custom transformations and apply complex logic to your data.
- Query Dependencies: Power Query provides a way to create reusable query steps and organize them into a sequence. This makes it easier to manage and maintain complex data transformation workflows.
- Applied Steps: Each transformation you apply in Power Query is recorded as an "applied step." These steps are displayed in a sequential order, and you can go back and modify any step to adjust the data transformation process.
- Query Folding: Power Query tries to optimize data retrieval by pushing certain transformation steps back to the data source whenever possible. This is known as query folding and can improve performance.
