Explore and Analyze Data41% of the exam
Logical, number, aggregate and spatial calculations
Write IF, CASE and IIF tests that handle nulls the way a requirement asks, pick ROUND, CEILING, FLOOR, DIV or INT (and formatting) for numbers, keep aggregate and row-level values apart, and build points, lines, radius zones and distances with MAKEPOINT, MAKELINE, BUFFER and DISTANCE.
Create calculated fields: Write date calculations; Write string functions; Write logical and Boolean expressions; Write number functions; Write type conversion functions; Write aggregate functions; Write basic spatial calculations.
~8 min read · 8 practice questions ·
What the exam expects
- Write IF, ELSEIF, CASE and IIF expressions, predict which branch fires when tests overlap, and send null values to the label the requirement asks for.
- Choose between ZN, IFNULL and ISNULL for null handling.
- Pick ROUND, CEILING, FLOOR, DIV or INT from the output a number needs, and know when number formatting beats ROUND.
- Fix "cannot mix aggregate and non-aggregate" errors and predict how an aggregate calculation behaves on a shelf.
- Build a basic spatial calculation with MAKEPOINT, MAKELINE, BUFFER or DISTANCE.
- Date, string and conversion functions: see Date, string and type conversion functions; first calculated fields: the Desktop Foundations unit Calculated fields and when to use parameters.
Key terms:
- Unknown result: a test that evaluates to null rather than true or false.
- Row-level calculation: computed at the data source level of detail, once per row.
- Aggregate calculation: computed at the visualization level of detail, once per mark.
- AGG(): the shelf name of an aggregate calculation, which cannot be aggregated further.
- Spatial point: a geometry built from latitude and longitude, the input to MAKELINE, BUFFER and DISTANCE.
Key facts
IF evaluation
- Detail
- Returns the THEN value for the first true test
No ELSE
- Detail
- IF or CASE with no match and no ELSE returns null
IIF unknown
- Detail
- Optional fourth argument returned when the test is null; omitted means null
ZN
- Detail
- Returns the expression, or 0 when null
INT
- Detail
- Truncates toward zero
DIV
- Detail
- Returns the integer part of a division
ROUND precision
- Detail
- Formatting may be preferable to ROUND because of floating point representation
Mixing rule
- Detail
- An aggregated and a disaggregated value cannot be combined
Aggregate result
- Detail
- Always a measure, shown as AGG(name) on a shelf
MAKEPOINT input
- Detail
- Native latitude and longitude columns, latitude first
BUFFER on a point
- Detail
- Polygon centered on the point, radius = distance and units
DISTANCE
- Detail
- Returns a number; created only on a live connection
Sources for this section (5)
- What does an IF return for a row that matches no test when there is no ELSE?
- Why can't every IF be rewritten as a CASE?
- Can a negative decimals argument make ROUND round to hundreds on any data source?
- Why is MAX(SUM([Sales]), [Profit]) invalid?
- Which argument comes first in MAKEPOINT?
The questions are free to read. Answers with their sources and self-grading are included with the pack.
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