Data processing: database and file management or data structures – Database design – Data structure types
Reexamination Certificate
1999-01-08
2004-08-03
Corrielus, Jean M. (Department: 2172)
Data processing: database and file management or data structures
Database design
Data structure types
C707S793000, C707S793000, C707S793000
Reexamination Certificate
active
06772164
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to a database system, in particular to a database system in which a database comprising a plurality of data sets is stored, further a method for storing, amending, and displaying the database, as well as a method for searching in respectively for accessing to the database.
BACKGROUND OF THE INVENTION
A database system usually comprises a stock of data, the so-called database, which is stored in a machine-readable storage, as well as a data processing system on which one or more application programs are running, in order to be able to access the database by means of a control program, the so-called database management system, as well as to be able to display components of the database, to search for components, and to modify the database, to input new data, etc.
The interpretation of the data in the database is done by means of metadata, which are “data about the data”, said metadata being required by said database management system and being separately stored by said system. The metadata are data descriptive for the fields of the data sets and for all other attributes of the database system.
In all known database systems the database is stored in a structured form, according to the state of the art in form of a table. The database thereby comprises individual data sets, which again consist of individual data fields. If the information in the data sets is dividable into several fields, with the meaning of the n-th field in each data set being identical, then this is storage in a structured form. The contents of the fields may be different.
An example for such a structured database in the form of a table is shown in FIG.
2
.
The individual data sets are the rows of the table, in which in respective individual data fields information is contained about receipt number, date, first name, last name, and type of the receipt. The last field of each data set contains a set number, which is an identification number to unambiguously identify the data set. All data sets not only have the same number of data fields, the data fields of each data set also can be categorized according to a structure which is common to all data sets.
For example, each data set contains a field which may be described or identified as receipt number, another one as the date, another one as the first name, etc. The individual data sets are put together into a table the columns of which are characterized by a common description of their content. The structure of the table therefore is prescribed by the descriptions which are present in the header of the table of FIG.
2
. The fields of the table header contain further information which is not shown about the content of the individual columns of the table, so-called metadata for the individual fields of the data sets of the table. Basically, in conventional database systems, data of the database are stored in such a structured form, which means there is a prescribed table structure into which the data sets to be stored have to fit with respect to the number of fields and with respect to the description of the field content, however, also with respect to the data type or the data structure of the content of the field.
Because of the prescribed structure according to which the data have to be stored, it is not possible in conventional database systems in case of a structure according to
FIG. 2
to store further information which does not fit into this structure. For example, if only for some of the data sets additional information is to be stored, then for this purpose the structure of all of the stored data has to be changed. An example is shown in FIG.
3
.
In order to further store a department identifier, even if this information is to be stored only for some of the data sets, an additional column “department” has to be inserted into the table.
Therefore, in conventional database systems, there is a prescribed structure which is mandatory for the individual data sets, and the individual data sets then are combined into a table as shown in
FIG. 2
or in FIG.
3
. Thereby there exists a prescription for the individual data sets with respect to their description but also with respect to their data format by the overall structure of the table which is formed by the data sets. With respect to their description, their data format, so to speak with respect to their metadata, the contents of the individual fields of the data sets may only be amended by amending the overall structure of the table as a whole. However, such an amendment of the structure of the whole table, like the amendment from
FIG. 2
into the one of
FIG. 3
influences the structure of all, also the already existing data sets.
The data sets being combined into a table are called the database table. The sum of the metadata of all database tables of the database, which themselves may be individually different, form the so-called data model of the database system.
This kind of structured storage of the data means that for each storage of data sets it is required that the data sets which are to be stored with respect to their structure fit at least into a partial structure of the database.
Therefore, if a data set is to be stored the structure of which is not in accordance with the existing data structures or, with parts thereof, then the database has to be extended by the new structure element (field/fields) before the data set can be stored.
The data structure resulting from the tables not only is formed in the database itself but also is reflected in the database management system as well as in the application programs. For this reason the following problems arise.
Requests for amendments with respect to the data structure are input by the users and therefore at first are forwarded to the application software. However, this then leads also to an amendment of the data model of the database. Furthermore, the amendments of the user requirements have to be defined by the user, and if they are realized they lead to amendments in the database management system, since this system has to be adapted to the structure of the database. This results in a continuing degeneration of the data structures. For example, it may happen that when inserting new columns, not all fields of the column are written into, thereby some of the fields of the whole table which is formed of the individual data sets remain empty.
A particular problem is the storage of data sets having a new data set structure. This data set structure has to be defined by the user. For this purpose amendments in the database management system as well as in the application programs are necessary.
The structured storage of the data in the form of a table therefore leads to a lot of work to be done by the system administrator as a result of the requirements or the demands set forth by the users towards the database. The structure of the database has to be adapted and amended continuously.
In conventional database systems the data sets are ordered in the form of a table. Each data set consists of several data fields. Each data field consists of a descriptor and a field value (field content). The descriptor thereby describes the field value. This means that the descriptor describes the fields with respect to the type respectively the meaning of their field values. For example, all data fields, the contents of which are “body size” have the same descriptor. Based on these structured data sets then the structured database is formed in the form of a table. This conventional method requires confirmed or hypothetic information about the structure of the data sets to be stored. These information are required in order to define the data model which enables the storage of all data sets, which potentially have to be stored based on the existing information. To store the usually inhomogenious overall set of expected data sets, database tables are defined, whereas each database table only stores data sets having the same structure. The sum of all definitions of all database tables forms the abstract data model of the datab
Corrielus Jean M.
Ser Solutions, Inc.
Wilmer Cutler Pickering Hale and Dorr LLP
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