EXISTS clause and examples - Simple Log Service - Alibaba Cloud Documentation Center

The EXISTS clause evaluates to TRUE if the specified subquery returns one or more rows, causing the outer SQL statement to execute.

Syntax

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

Parameters

Parameter	Description
subquery	The `subquery` is a `SELECT` statement.

Example

The following statement retrieves consumer group information when the read/write latency in a Logstore exceeds 1000.

Query and analysis 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
  )

The query and analysis result contains the consumer_group column. An example value is sls-ml-ag****ea76a483d4 (partially masked).