ApsaraDB for OceanBase:Modify, drop, and add column attributes

Syntax

column_clauses:
{ { add_column_clause
  | modify_column_clauses
  | drop_column_clause
  | add_period_clause
  | drop_period_clause
  }...
| rename_column_clause
| { modify_collection_retrieval }...
| { modify_LOB_storage_clause }...
| { alter_varray_col_properties }...
}

add_column_clause:
ADD
   ( {column_definition | virtual_column_definition
      [, column_definition | virtual_column_definition] ...
     } )
   [ column_properties ]
   [ ( out_of_line_part_storage [, out_of_line_part_storage]... ) ]

modify_column_clauses:
MODIFY
{ ( modify_col_properties | modify_virtcol_properties
    [, modify_col_properties | modify_virtcol_properties ]... )
| ( modify_col_visibility [, modify_col_visibility ]... )
| modify_col_substitutable
}

drop_column_clause:
{ SET UNUSED { COLUMN column
             | (column [, column ]...)
             }
  [ { CASCADE CONSTRAINTS | INVALIDATE }... ]
  [ ONLINE ]
| DROP { COLUMN column
       | (column [, column ]...)
       }
  [ { CASCADE CONSTRAINTS | INVALIDATE }... ]
  [ CHECKPOINT integer ]
| DROP { UNUSED COLUMNS
       | COLUMNS CONTINUE
       }
  [ CHECKPOINT integer ]
}

add_period_clause:
ADD ( period_definition )

drop_period_clause:
DROP ( PERIOD FOR valid_time_column )

rename_column_clause:
RENAME COLUMN old_name TO new_name

modify_collection_retrieval:
MODIFY NESTED TABLE collection_item
RETURN AS { LOCATOR | VALUE }

modify_LOB_storage_clause:
MODIFY LOB (LOB_item)
   (modify_LOB_parameters)

alter_varray_col_properties:
MODIFY VARRAY varray_item
   ( modify_LOB_parameters )

Supported operations

• Renaming columns by using the rename_column_clause clause is supported. For more information, see Modify, drop, and add column attributes.

• Adding columns and constraint attributes by using the add_column_clauses clause is supported. For more information, see Add columns and column attributes.

• Modifying column attributes by using the modify_column_clauses clause is supported. For more information, see Modify column attributes.

• Dropping columns by using the drop_column_clause clause is supported. For more information, see Drop columns.

Unsupported operations

• Modifying the result set retrieved from the database by using the modify_collection_retrieval clause is not supported. An error will be returned when you perform this operation.

• Modifying the physical attribute of the LOB_item by using the modify_LOB_storage_clause clause is not supported. An error will be returned when you perform this operation.

• Modifying the LOB storage characteristics of the VARRAY type by using the alter_varray_col_properties clause is not supported. An error will be returned when you perform this operation.