CASE
WHEN REGEXP_MATCH(Source, "^.(google).") AND REGEXP_MATCH(Medium, "^.(cpc).") THEN "Paid Search"

WHEN REGEXP_MATCH(Default Channel Grouping, "^.*(Direct).*") THEN "Direct"
WHEN REGEXP_MATCH(Default Channel Grouping, "^.*(Organic).*") THEN "Organic"
WHEN REGEXP_MATCH(Default Channel Grouping, "^.*(Referral).*") THEN "Media"
WHEN REGEXP_MATCH(Default Channel Grouping, "^.*(Social).*") THEN "Social"
WHEN REGEXP_MATCH(Default Channel Grouping, "^.*(Email).*") THEN "Email"

ELSE "Other Advertising" END