NULLIF

Syntax

NULLIF(expr1, expr2)

AMC specifics

• Classic use: avoid division by zero by turning a zero denominator into NULL.
• The division then returns NULL instead of an error.

Example

Click-through rate without an error at zero impressions.

SELECT
  campaign,
  SUM(clicks) / NULLIF(SUM(impressions), 0) AS ctr
FROM
  sponsored_ads_traffic
GROUP BY
  1

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