# ASSERT SCHEMA statement in ksqlDB for Confluent Platform ## Synopsis ```sql ASSERT (NOT EXISTS)? SCHEMA (SUBJECT subjectName)? (ID id)? (TIMEOUT timeout); ``` ## Description Asserts that a schema exists or does not exist. Schemas can be specifed by either their subject name, id or both. The `TIMEOUT` clause specifies the amount of time to wait for the assertion to succeed before failing. If the `TIMEOUT` clause is not present, then ksqlDB will use the timeout specified by the server configuration `ksql.assert.schema.default.timeout.ms`, which is 1000 ms by default. If the assertion fails, then an error will be returned.