anchor.diff:      : (columnName | attributeName) (DEFAULT expr)? (inlineConstraint* | inlineRefConstraint?) | outOfLineConstraint | outOfLineRefConstraint
       ;
   
  -
  +renameIndexClause_
  +    : (RENAME TO indexName)?
  +    ;
  
positive.code:     : (tableName | alias)? columnName (ASC | DESC)?
      ;
  
  tableAlias
      : tableName alias? (COMMA_ tableName alias?)*
      ;
  
  alterClause_
      : (alterTableProperties | columnClauses | constraintClauses | alterExternalTable)?
      ;
  
  
negative.code:     ;
  
  createIndex
      : CREATE createIndexSpecification_ INDEX indexName ON createIndexDefinitionClause_
      ;
  
  alterTable
      : ALTER TABLE tableName alterDefinitionClause_
      ;
  
  // TODO hongjun throw exeption when alter index on oracle
  alterIndex
      : ALTER INDEX indexName renameIndexClause_
      ;
  
  dropTable
  