An EXISTS clause is used to check whether a subquery returns a specific result. If the subquery in an EXISTS clause returns a specific result, true is returned and the outer SQL statement is executed.
Syntax
SELECT...FROM...WHERE EXISTS (subquery)Parameters
Parameter | Description |
Parameter | Description |
subquery | The value of this parameter is a SELECT statement. |
Example
Check whether the read and write latency of a specific Logstore is greater than 1,000 microseconds. If the latency is greater than 1,000 microseconds, the information of the related consumer group is returned.
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 )Query and analysis result
