PDE Ingesting and Processing the Data Practice Question
A data analyst needs to transform nested and repeated fields in BigQuery. They have a table with a column of type ARRAY<STRUCT<...>>. Which SQL function should they use to flatten the array into individual rows for analysis?
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
UNNEST
UNNEST is used to flatten arrays into rows. STRUCT is used to group fields. CAST is for type conversion. REPLACE is for string replacement.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
STRUCT
Why it's wrong here
STRUCT creates a struct, not flattens.
- ✗
CAST
Why it's wrong here
CAST converts data types.
- ✓
UNNEST
Why this is correct
UNNEST converts array elements into rows, allowing analysis of nested data.
- ✗
REPLACE
Why it's wrong here
REPLACE substitutes string values.
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