HAVING

WHERE filters input rows before grouping. HAVING filters grouped or aggregated results after grouping.

Examples

Find days where the average CPU utilization exceeded 80%:

SELECT
  date_trunc('day', ts) AS day,
  AVG(cpu_util) AS avg_cpu_util
FROM
  system_metrics
GROUP BY
  day
HAVING
  avg_cpu_util > 80;

Find hours where the number of error logs is greater than 100:

SELECT
  DATE_TRUNC('hour', log_time) AS hour,
  COUNT(*) AS error_count
FROM
  application_logs
WHERE
  log_level = 'ERROR'
GROUP BY
  hour
HAVING
  error_count > 100;