Marketing Cloud Developers Certification Practice Test

In Marketing Cloud's Query Activity, you must list columns explicitly in the SELECT clause. Using a wildcard (SELECT *) is not permitted, and it’s especially problematic when a join is involved because the resulting column names from both tables can clash or be unclear. That’s why the pattern that combines a join with a SELECT * is not allowed. Patterns that are allowed include joining with an explicit column list, running a query without a join, and adding a WHERE clause to filter results. The key practice is to specify exactly which columns you want, keeping the output predictable and unambiguous.