COALESCE

Syntax

COALESCE(expression [, expression]*)

AMC specifics

• All expressions must have the same type. IFNULL and NVL are aliases of COALESCE.
• COALESCE helps with GREATEST and LEAST, where a single NULL turns the whole result into NULL.

Example

Report missing campaign names as their own "unknown" row.

SELECT
  COALESCE(campaign, 'unknown') AS campaign_name,
  SUM(impressions) AS impressions
FROM
  sponsored_ads_traffic
GROUP BY
  1

Checked against the AMC schema, not executed on an AMC instance.