Does DISTINCT scope to the first column?

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Accepted Answer

DISTINCT is not a function - it applies to the entire row, not just the first column. A row is a duplicate only if all selected column values are the same. Two employees named 'Alice Johnson' and 'Alice Smith' have the same first_name but different last_name - they are NOT duplicates and both appear. This surprises many developers who expect DISTINCT to operate per-column.