Method and apparatus for redefining a group of related objects in a relational database system
View Patent ↗Techniques for redefining a group of related objects in a relational database system by redefining a table belonging to the group of related objects and then redefining the other related objects in the group so that they are in conformity with the redefined table. The techniques permit DDL to be used to redefine a view and are also useful in a versioned relational database system for redefining the table from which the versions are generated. In the versioned relational database system which employs the technique, the versions are generated from a view. To redefine the view, the technique is employed as follows: the view's definition in the relational database system is used to make a base table that has a form which is substantially similar to that of the view. DDL is then applied to the base table to redefine it. The redefined base table definition and the definitions of the objects belonging to the versioned relational database system are then used to redefine the definitions of the objects belonging to the versioned relational database system so that they are in conformity with the base table as redefined by the DDL.
1. Apparatus for redefining objects belonging to a group of related objects in a relational database system, the group of related objects including a table that is not a base table, the related objects having definitions in the database system, and the apparatus comprising:
a base table definition maker that receives the definition for the table that is not a base table and makes a base table definition and a base table therefrom;
a table redefiner that receives input redefining the base table and produces a redefined table definition in response thereto; and
a transformer that responds to the redefined table definition and to the definitions for objects in the group of related objects to automatically redefine the definitions as required to bring the objects in the group into conformity with the base table as redefined by the input.
2. The apparatus set forth in claim 1 wherein:
the input redefining the base table is a statement in a data definition language.
3. The apparatus set forth in claim 2 wherein:
the data definition language is the SQL DDL language.
4. The apparatus set forth in claim 1 wherein:
the apparatus includes a graphical user interface for redefining the base table; and
the input redefining the given table is received from the graphical user interface.
5. The apparatus set forth in claim 1 wherein:
the table whose definition is received by the base table definition maker is a view.
6. The apparatus set forth in claim 5 wherein:
the base table has substantially the same form as the view.
7. The apparatus for redefining objects set forth in claim 1 wherein:
the table that is not a base table is a view; and
the table redefiner is an SQL parser that applies a DDL statement to the base table definition made from the view to produce a redefined definition therefor.
8. A method for redefining objects belonging to a group of related objects in a relational database system, the group of related objects including a table that is not a base table, the related objects having definitions in the database system, and the method comprising the steps of:
making a base table and a definition therefor from the table that is not a base table;
receiving input in the relational database system that redefines the base table;
responding to the input in the relational database system by producing a redefined table definition for the base table; and
responding to the redefined table definition and to the definitions for objects in the group of related objects in the relational database system by automatically redefining the definitions as required to bring the objects in the group into conformity with the base table as redefined by the input.
9. The method set forth in claim 7 wherein:
the input redefining the base table is a statement in a data definition language.
10. The method set forth in claim 8 wherein:
the data definition language is the SQL DDL language.
11. The method set forth in claim 7 wherein:
the relational database system includes a graphical user interface for redefining the base table; and
in the step of providing input, the input is provided using the graphical user interface.
12. The method set forth in claim 7 wherein:
the table from whose definition the base table and the definition therefor are made is a view.
13. The method set forth in claim 11 wherein:
the base table has substantially the same form as the view.
14. The method of redefining objects set forth in claim 8 wherein:
the table that is not a base table is a view;
in the step of receiving input, the input is a DDL statement; and
in the step of responding to the input, the redefined table definition for the base table is produced by applying the DDL statement to the base table definition made form the view.
15. A data storage device that is readable by a processor, the storage device being characterized in that:
the storage device contains data representing a program which, when executed by the processor, performs the method set forth in claim 14 .
16. A data storage device that is readable by a processor, the storage device being characterized in that:
the storage device contains data representing a program which, when executed by the processor, performs a method for redefining objects belonging to a group of related objects in a relational database system, the group of related objects including a table that is not a base table, the related objects having definitions in the database system, and the method comprising the steps of:
making a base table and a definition therefor from the definition for the table that is not a base table;
receiving input in the relational database system that redefines the base table;
responding to the input in the relational database system by producing a redefined table definition for the base table; and
responding to the redefined table definition and to the definitions for objects in the group of related objects in the relational database system by automatically redefining the definitions as required to bring the objects in the group into conformity with the base table as redefined by the input.