ClickHouse 错误Received from localhost:9000. DB::Exception: Cannot convert NULL value to non-Nullable

错误：Code: 349. DB::Exception: Received from localhost:9000. DB::Exception: Cannot convert NULL value to non-Nullable type: while converting source column salary to destination column salary: while executing 'FUNCTION _CAST(salary :: 2, Int16 :: 7) -> _CAST(salary, Int16) Int16 : 6'. (CANNOT_INSERT_NULL_IN_ORDINARY_COLUMN)

解决方案：clickhouse不能将MySQL中的null转换，所以导致报错