medium10 pts · first answer countswindow-functionssqldata-cleaning

Marking duplicates in an UPDATE

You want to set is_duplicate = true on every copy except the first per email. Why can't you write ROW_NUMBER() directly in the UPDATE's WHERE?

A.Windows are not allowed in WHERE; compute rn in a CTE and joinB.UPDATE statements cannot read from the same tableC.ROW_NUMBER only works in SELECT with an ORDER BY at the endD.Booleans cannot be set using window results

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Marking duplicates in an UPDATE

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