The weekly engagement report counts reviews with the expression SELECT count(comment_text) FROM catalog.reviews. The reported number comes out lower than the table's actual row count, and QA confirms that many customers submit a star rating only, leaving comment_text NULL. The report must count every review. Which expression and explanation are correct?

1. A. count(comment_text) counts every row, NULLs included, so the missing reviews must be dropped somewhere else in the pipeline 💬 A
2. B. count(*) skips any row that contains a NULL in one of its columns, so both expressions under-report on nullable tables 💬 B
3. C. count(expr) counts only rows where expr is not NULL; count(*) counts every row, so the report needs count(*) to total all reviews ✓ C
4. D. count(*) and count(col) are equivalent and always return the same number, so the shortfall must come from a stale result cache 💬 D

Revelar gabarito

Resposta correta: count(expr) counts only rows where expr is not NULL; count(*) counts every row, so the report needs count(*) to total all reviews

Referência: https://docs.databricks.com/aws/en/sql/language-manual/sql-ref-functions