What does the grain of a table mean?
Grain describes what one row represents. An order table may have one row per order while an order-line table has one row per item in an order.
How should I handle blank values in a report?
Find out whether a blank means missing, unknown or inapplicable. Replace it with zero only when zero has the correct business meaning.
What is a SQL window function used for?
It calculates across related rows while preserving each row in the result. A running total per customer is one example.
When should I use UNION ALL in SQL?
Use it when appending rows from compatible queries and keeping duplicates. UNION removes duplicate result rows.
Why does COUNT(*) differ from COUNT(column)?
COUNT(*) counts all result rows. COUNT(column) skips rows where the specified column is null.
What does Power Query do in Power BI?
It imports and transforms data. Common steps include setting types, removing unwanted columns and combining files.
Why use a separate date table in Power BI?
A date table gives reports a consistent calendar for filtering and grouping, including dates with no transactions.
When is a line chart useful in a dashboard?
Use it to show how a value changes over an ordered interval such as weeks or months. Clearly label gaps or incomplete periods.
What is a KPI in a dashboard?
A key performance indicator measures progress toward a stated goal. Include the definition, time period and target so readers can interpret it.
How should I document an analytics project?
State the question, data source, grain, cleaning decisions and metric definitions. Include a check that reconciles the final numbers with the input.
See the beginner Q&A guide for related topics.
