Power BI PL-300 练习

Power Query is the data preparation tool in Power BI. It imports data and applies cleaning and transformation steps before the data is loaded into the model. DAX, layouts, and subscriptions are different features.

A data refresh pulls the latest values from the original data sources into Power BI. It does not change themes, delete reports, or move workspaces.

Power Query Editor is where you clean and transform data before loading it into the model. DAX Studio is an external tool, while Report and Model views are used for other tasks.

Promote Headers makes the first row of a table the column names. Sorting, removing blanks, and creating tables are separate Power Query actions.

Correct data types allow Power BI to calculate, sort, and visualize values accurately. Data types do not control titles, file size, or dataset names.

Remove Duplicates keeps only unique rows based on the selected columns. It does not delete the table or all columns, and it is not a sorting operation.

A query parameter is a named value you can reuse in M code, such as a file path or filter value. It is not a relationship, bookmark, or refresh schedule.

Power Query connects to many sources, including Excel, SQL Server, text files, and web services. It is not limited to a single source type.

Append Queries stacks rows from tables that have the same structure. Joining by key columns is called Merge Queries, not append.

Merge Queries joins tables based on matching key columns, like a SQL join. Appending stacks rows instead, and report pages are not merged by this feature.

A dataflow contains reusable data transformation logic hosted in Power BI. Reports and datasets can use it as a shared source, which reduces duplicated preparation work.

Scheduled refresh updates datasets from their sources on a schedule. Auto summarize and quick insights are modeling and analysis features, not refresh schedules.

A data gateway securely transfers data between Power BI cloud services and on-premises sources. It is not an internet accelerator or report generator.

Power Query uses the M formula language. DAX is used for measures in the data model, SQL queries databases, and Python is a general programming language.

This statement is true. Power Query can import and combine data from multiple sources using append, merge, and custom transformation steps.

Power Query uses the M formula language for transformation steps. M expressions appear in the Advanced Editor and define how data is loaded and shaped.

A star schema has a central fact table linked to dimension tables. This design reduces redundancy and improves model performance. It is not a flat table or security role.

A fact table stores numeric values and business transactions that can be aggregated. Descriptive labels belong in dimension tables.

Dimension tables provide descriptive attributes like product, customer, or date labels. Fact tables hold numeric transactions and measures.

A relationship links tables by matching columns, usually keys, so filters and calculations flow between them. Bookmarks, schedules, and tooltips are different features.

A one-to-many relationship means one value in the primary table can be referenced by many rows in the related table. This is the most common relationship in Power BI models.

Cross filter direction determines whether filters flow from one table to the other, both ways, or not at all. It does not control page scrolling, refresh, or bookmarks.

A calculated column is computed for every row and stored in the table. Measures are evaluated at query time, and filters are separate from calculated columns.

A measure is a DAX calculation that runs when the report is queried and responds to filters. It is not stored as a column and is not a data source.

FILTER returns a table based on a condition. SUM aggregates values, FORMAT changes text, and USERNAME returns the current user name.

CALCULATE modifies the filter context of a measure. COUNTROWS counts rows, RELATED fetches a related value, and VALUES returns distinct values.

SUM adds numeric values in a column. COUNTA counts non-empty values, MAX returns the largest value, and DISTINCT returns unique values.

SUMX iterates over rows and sums an expression for each row. SUM works on a single column, ADDCOLUMNS adds columns, and CONCATENATE joins text.

ALL removes filters so calculations can ignore the current filter context. It is commonly used inside CALCULATE for percentages and totals.

COUNTROWS returns the number of rows in a table. SUM adds values, CALCULATE changes filters, and FIRSTNONBLANK returns the first non-blank value.

RELATED fetches a value from a related table based on the relationship. It does not create relationships, refresh data, or filter visuals directly.

Time intelligence functions such as SAMEPERIODLASTYEAR and DATEADD compare values across periods. Text, filter, and math functions serve other purposes.

This statement is false. Measures are calculated at query time and are not physically stored in the table. Calculated columns are stored, but measures are not.

This statement is true. CALCULATE changes the filter context by adding or removing filters before evaluating an expression. It is one of the most important DAX functions.

CALCULATE changes the filter context of an expression. It can add, remove, or replace filters and is essential for advanced DAX measures.

A hierarchy defines drill-down levels such as year, quarter, and month. It lets users navigate from a summary to more detail. It is not security, refresh, or a bookmark.

Row-level security filters data so different users see only allowed rows. It does not hide reports, encrypt files, or block refresh.

A role contains row filters and is assigned to users or groups. RLS roles control what data each user can view in a report.

A star schema reduces redundancy and makes filters flow clearly from dimensions to facts. This improves calculation speed and model maintainability.

A composite model can include multiple data sources and storage modes such as Import and DirectQuery in one model. It is not limited to one file or source.

A slicer is an interactive visual filter on a report page. Users select values to filter other visuals. It is not a page, schedule, or measure.

A bookmark captures the current state of a report page, including filters and visibility. It is used to create story-like navigation in reports.

Drillthrough lets users click a value and open a detail page focused on that entity. It is not resizing, exporting, or changing themes.

A tooltip page appears when a user hovers over a visual and can show extra context. It is not a print layout, source, or security role.

Bar and column charts compare values across categories clearly. Cards show single values, slicers filter, and Q&A answers natural language questions.

A matrix displays values in rows and columns and can include subtotals and grand totals. A card shows one number, and a map displays geographic data.

A card visual displays one value, such as total sales. Tables, maps, and bookmark panes are different elements.

A KPI visual compares a measure to a target and shows progress. It is not a filter, page, or source editor.

A report page is a canvas where visuals are arranged. Reports can have multiple pages, each with its own layout and visuals.

A dashboard is a single canvas containing tiles pinned from reports or created directly in the service. It is not a paginated report, dataflow, or parameter.

A workspace organizes content such as reports, datasets, and dashboards for a team. It is not a visual, gateway, or formula.

A Power BI app packages reports and dashboards so content can be shared with a broad audience. It is not hardware, a source, or a query step.

A subscription sends report or dashboard content by email on a schedule. It is not a license, model, or bookmark.

Sharing gives other users access to a report in the service. It does not let them edit sources, change Power Query, or install software.

Paginated reports are designed for fixed, printable layouts with pixel-perfect formatting. Interactive dashboards, Q&A, and RLS are different features.

This statement is true. Users can pin report visuals to dashboards so the tiles appear on a single canvas in the Power BI service.

This statement is true. Power BI provides a mobile layout editor where you arrange visuals for phones separately from the desktop layout.

Performance Analyzer records load time and query time for report visuals. It helps identify slow visuals. It is not a theme, source, or subscription tool.

Q&A lets users type natural language questions and get visual answers. Bookmarks save states, drillthrough navigates details, and Performance Analyzer measures speed.

Users can export underlying visual data to Excel or another format from the report. Dataflows, gateways, and bookmarks do not export visual data.