您好，
sql 出现以下错误，是什么原因造成的呀？
Flink SQL> insert overwrite pmw select '1';
[INFO] Submitting SQL update statement to the cluster...
[ERROR] Could not execute SQL statement. Reason:
org.apache.flink.table.api.TableException: Stream Tables can only be emitted by
AppendStreamTableSink, RetractStreamTableSink, or UpsertStreamTableSink.
