COMMENT - ApsaraDB for OceanBase - Alibaba Cloud Documentation Center

This topic describes the conversion scope of COMMENT DDL operations during data migration from an Oracle database to an Oracle tenant of OceanBase Database.

Syntax

COMMENT ON
  { AUDIT POLICY policy
  | COLUMN [ schema. ]
      { table. | view. | materialized_view. } column
  | EDITION edition_name
  | INDEXTYPE [ schema. ] indextype
  | MATERIALIZED VIEW materialized_view
  | MINING MODEL [ schema. ] model
  | OPERATOR [ schema. ] operator
  | TABLE [ schema. ] { table | view }
  }
  IS string ;

Supported operations

Commenting on a table by using the COMMENT ON TABLE clause is supported. Sample code:
```
COMMENT ON TABLE T IS 'test';
```
Commenting on a column by using the COMMENT ON COLUMN clause is supported. Sample code:
```
COMMENT ON COLUMN TEST_DATE.V_DATE IS 'Date'
```

Unsupported operations

Commenting on an audit policy by using the COMMENT ON AUDIT POLICY clause is not supported.
Commenting on an edition by using the COMMENT ON EDITION clause is not supported.
Commenting on an index type by using the COMMENT ON INDEXTYPE clause is not supported.
Commenting on a materialized view by using the COMMENT ON MATERIALIZED VIEW clause is not supported.
Commenting on a mining model by using the COMMENT ON MINING MODEL clause is not supported.
Commenting on a operator by using theCOMMENT ON OPERATOR clause is not supported.