> Mishandling Excessive Case When Statements User Defined Functions (UDFs) are another option to consolidate the logic in one place. > Using Functions on Inde

> Mishandling Excessive Case When Statements User Defined Functions (UDFs) are another option to consolidate the logic in one place. > Using Functions on Indexed Columns In other words, the query is not sargable [0] > Overusing DISTINCT to “Fix” Duplicates Orthogonal to author's point about dealing with fanout from joins, I'm a fan of using something like this for 'de-duping' records that aren't exact matches in order to conform the output to the table grain: ROW_NUMBER() OVER (PARTITION BY <grain> ORDER BY <deterministic sort>) = 1 Some database engines have QUALIFY [1], which lends itself to a fairly clean query. [0] https://en.wikipedia.org/wiki/Sargable https://en.wikipedia.org/wiki/Sargable [1] https://docs.aws.amazon.com/redshift/latest/dg/r_QUALIFY_clause.html https://docs.aws.amazon.com/redshift/latest/dg/r_QUALIFY_cla...