Use the EXISTS clause to check if a subquery returns results - Simple Log Service

The EXISTS clause tests for the existence of rows in a subquery. If the subquery returns at least one row, EXISTS evaluates to true and the outer SQL statement executes.

Syntax

SELECT...FROM...WHERE EXISTS (subquery)

Parameters

Parameter	Description
subquery	An arbitrary SELECT statement.

Example

Check whether the read/write latency of a Logstore is greater than 1000. If so, the query returns the consumer group information.

Query statement

* |
SELECT
  consumer_group
FROM  "internal-diagnostic_log"
WHERE
  EXISTS (
    SELECT
     Latency
    FROM     internal-operation_log
    WHERE
      "internal-diagnostic_log".Logstore = "internal-operation_log".Logstore and latency >1000
  )

Results