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PL-300 - Prepare the Data (24% of the exam) - Section 1.2

Clean, transform, and load data using Power Query Editor.

Use Power Query Editor to apply column transformations, correct data type conversion errors, and merge or append queries into a single clean table. Recognise that each applied step is recorded and replayable, so the order of steps affects the final output.

Power Query Editorapplied stepsdata type conversionmerging and appending queriescolumn transformations

Practice question for this objective

Free samplePrepare the Datamedium

An analyst wants to change the data type of a column in the Power Query Editor. Which locations in the editor expose a control for changing a column's data type? (Select 3 answers)

  • AThe icon on the left side of the column heading itself opens a data type picker. Correct
  • BThe Home tab Transform group exposes a Data type dropdown menu for the selected column. Correct
  • CThe column shortcut menu has a Change Type submenu that lists the available types. Correct
  • DThe View tab Layout group has a Data type button that opens the type picker.
  • EThe Add Column tab Custom group exposes a Data type dropdown that retypes existing columns.
Data type can be changed from the column heading icon, the Home tab, the Transform tab, or the column shortcut menu. The Data Types article lists four locations to define or change a column data type: the Data type dropdown in the Transform group on the Home tab, the Data type dropdown in the Any column group on the Transform tab, the icon on the left side of the column heading, and the Change Type entry on the column shortcut menu. Options A, B, and C correspond to three of these four.

Why A is correct: Correct. The icon on the left side of the column heading itself opens a data type picker is one of the keyed answers. The Data Types article lists four locations to define or change a column data type: the Data type dropdown in the Transform group on the Home tab, the Data type dropdown in the Any column group on the Transform tab, the icon on the left side of the column heading, and the Change Type entry on the column shortcut menu.

Why B is correct: Correct. The Home tab Transform group exposes a Data type dropdown menu for the selected column is one of the keyed answers. The Data Types article lists four locations to define or change a column data type: the Data type dropdown in the Transform group on the Home tab, the Data type dropdown in the Any column group on the Transform tab, the icon on the left side of the column heading, and the Change Type entry on the column shortcut menu.

Why C is correct: Correct. The column shortcut menu has a Change Type submenu that lists the available types is one of the keyed answers. The Data Types article lists four locations to define or change a column data type: the Data type dropdown in the Transform group on the Home tab, the Data type dropdown in the Any column group on the Transform tab, the icon on the left side of the column heading, and the Change Type entry on the column shortcut menu.

Why D is wrong: The View tab governs data preview options such as profiling and the formula bar, not data type assignment. There is no Layout group with a Data type button.

Why E is wrong: Add Column commands create new columns; they do not retype existing ones. Data type changes for existing columns live on Home and Transform.

See more PL-300 practice questions, answers explained.

Exam traps in Prepare the Data

Answers that look right on this material and are not. Each one is a distractor from a different question in the PL-300 bank for this domain.

  • A new query named Append1 is created from A and B, and the original A and B queries are unchanged.

    Why it is wrong: Creating a third query without changing A or B is the behaviour of Append queries as new, not of Append queries from inside table A.

  • Yes

    Why it is wrong: Any columns can also surface nested non-scalar values as load-time errors in Excel workbooks or the Power BI Desktop data model, which makes them risky as a query's output.

  • A cell-level error has occurred, displaying Error in individual cells of the data preview.

    Why it is wrong: Cell-level errors do not block load and surface as Error in specific cells, with no yellow pane. The yellow pane is reserved for step-level failures.

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