JPH04216147A - Schemer structure management system - Google Patents

Abstract

PURPOSE:To perform schemer structure management in a state where a program for accessing a data base can be prepared without modifying a program even when the schemer structure of the data base is changed in an information processing system in which the data base is shared by plural workstations through a network. CONSTITUTION:Schemer expansion areas 221 and 321 are respectively provided in the external storage devices 22 and 32 of workstations 2 and 3 and the schemer structure stored in the schemer structure management area 121 of the external storage device 12 of a data base server 1 is expanded in the schemer expansion areas 221 and 321 of each workstation as a local schemer which is guaranteed for the identity with the schemer structure so that each workstation can prepare a program independently from the schemer structure of the data base server 1 when each workstation refers to its own local schemer.

Description

[Detailed description of the invention]

0001

[Industrial Field of Application] The present invention relates to an information processing system in which a plurality of workstations and a database server are connected via a network and the database server is shared by the plurality of workstations. This paper relates to a schema structure management method that enables the creation of programs independently of the system.

0002

2. Description of the Related Art Databases are constructed according to a schema structure, which is their basic concept. When creating a program using data stored in a database system, it is necessary to follow the schema structure managed by that database system, and the created program must follow the schema structure of the database system, that is, the schema definition. matches.

FIG. 3 is an explanatory diagram of a schema structure management method according to the prior art, in which 10 is a database server;
1 is the CPU of the database server, 102 is the external storage device of the database server, and 1021 is the external storage device 10.
2 is a schema structure management area provided in 2, 20 is a workstation, 201 is a CPU of the workstation, 202
is an external storage device of the workstation, and 40 is a network.

In the figure, a database constructed in an external storage device 102 of a database server 10 is formed according to a schema structure stored in a schema structure management area 1021 provided in a part of the external storage device. ing. A plurality of workstations 20 connected to the network 40 use a database access program to share the database server 10 connected to the network 40 and execute various tasks.

When the workstation 20 attempts to create a program that accesses the database of the database server 10, it is necessary to follow the schema structure, ie, schema definition, managed by the database server 10.

As described above, in the prior art, a program that accesses a database cannot be programmed unless the schema structure of the database is determined, and if the schema structure is changed, reprogramming is required. In order to correct this drawback, a method has been considered in which the schema definition is expanded into the program source at the time of compilation. For example, C. J. Date, “An I
Introduction to Database
System” can be mentioned.

[0007]

The conventional method of expanding the schema structure into the program source at the time of compilation has the problem that if the schema structure is changed, the program must be recompiled. An object of the present invention is to provide a schema structure management method that makes it possible to create a program that accesses a database without modifying the program created by the workstation even if the schema structure of the database is changed. .

[0008]

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a plurality of workstations (two workstations in FIG.
, 3), and a database server (1 in Figure 1) are connected via a network (4 in Figure 1), and the database server is shared by a plurality of workstations. A schema development area (221, 321 in Figure 1) is provided in the device (21, 31 in Figure 1), and a schema structure management area (221, 321 in Figure 1) of the external storage device (12 in Figure 1) of the database server is provided. 121) is deployed as a local schema that guarantees identity with the schema structure in a schema deployment area provided in an external storage device of the workstation, and the workstation refers to the local schema. It is characterized by making it possible to create programs.

[0009]

[Operation] Deploys the schema structure in the schema expansion area provided in the external storage device of the workstation as a local schema with a schema structure guaranteed to be identical to the schema structure stored in the schema structure management area of the external storage device of the database server. so that the workstation can refer to it independently. A workstation program that accesses a database in a database server refers to its own local schema information to recognize the schema structure of the database.

[0010] When the schema structure of the database is changed, the date and time of the change is inquired of the database,
It compares the date of its own local schema, and if the modification date and time on the database side is newer than the date of its own local schema, it acquires schema information from the database server and rebuilds the local schema. This ensures the sameness between the database schema structure and the local schema.

[0011] Therefore, each workstation can create a program that accesses the database server independently of the schema structure managed by the database server by referring to the local schema developed in its own external storage device. It becomes possible.

0012

Embodiments Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is an explanatory diagram of a network system to which an embodiment of the schema management method according to the present invention is applied, in which 1 is a database server, 11 is a CPU of the database server, 111 is a main storage device of the database server, and 12 is a database server. 121 is a schema structure management area that manages the schema structure of the database. Also,
2 and 3 are provided in the workstation, 21 and 31 are the CPUs of the workstation, 211 and 311 are the main storage devices of the workstation, 22 and 32 are external storage devices of the workstation, and 221 and 321 are provided in the external storage devices of the workstation. The schema development areas 23 and 33 are display devices.

As shown in FIG. 1, this embodiment is comprised of a database server 1 connected to a network 4, and a plurality of workstations 2 and 3 that share access to the database server 1. Although not shown, the network 4 is also connected to a mail server, a file server, a print server, and other information devices.

In the figure, workstations 2 and 3
Under the control of the CPUs 21 and 31, accesses the database server 1 using programs stored in the external storage devices 22 and 32, and executes various tasks. A program that accesses the database server 1 needs to follow the schema structure that defines the database built in the database server 1.

A program that accesses the database server 1 cannot be created without referring to the schema structure managed in the schema structure management area 121 of the external storage device 12 of the database server 1. In this embodiment, the external storage device 2 of each workstation 2, 3
Schema development areas 221 and 321 are provided in 2 and 32, and the schema information of the database managed in the schema structure management area 121 of the external storage device 12 of the database server 1 is developed there. Hereinafter, the schema information developed in the schema development areas 221 and 321 of the workstations 2 and 3 will be referred to as local schema.

A program that accesses the database of the database server 1 is stored in the schema development area 22 described above.
By referring to the local schema expanded to 1,321, it becomes possible to recognize the schema structure of the database.

Furthermore, when the schema structure managed by the database is changed, the database server 1 inquires of the database about the date and time of the change, and the workstations 2 and 3 transmit this date and time to their schema deployment areas 221 and 321. The schema information of the database server 1 is compared with the date and time when it was expanded, and if the changed date and time is newer than the expansion date and time of the local schema information, this is notified to the workstations 2 and 3. The workstations 2 and 3 acquire schema information from the database server 1 and reconstruct the local schema.

[0018] In the above explanation, the database server 1 monitors whether or not the schema has been changed, but the workstations 2 and 3 monitor the database server 1.
It is also possible to inquire the schema structure management area 121 of the user at the time of program creation or periodically, and compare the date and time when the schema information was developed in the own schema development area with the date and time when the schema structure of the database was changed.

[0019] This ensures the identity of the schema structure of the database and the local schema deployed on the workstation.

FIG. 2 is a flowchart illustrating a schema expansion operation when a workstation reconstructs its local schema. In the figure, first, the workstations 2 and 3 have their schema development areas 221 and 32
Check whether a local schema file (local schema file) exists in Step 1 (Step 1: hereinafter referred to as S-1).

[0021] If a local schema file exists, the database server 1 is inquired about the date and time when it was expanded, and the presence or absence of changes in the schema structure is checked, and if there is a change, the date and time of the change (schema definition date and time) and the above The development date and time are compared (S-2).

[0022] If the date and time of the modification of the schema structure is earlier than the date and time of expansion of the local schema, it is determined that there is no modification and the process ends. If the date and time of the modification of the schema structure is after the date and time of expansion of the local schema, it is determined that there has been a modification, and the schema information is acquired from the database server 1 and the local schema is reconfigured (S-3).

[0023] In (S-1), if the local schema file does not exist on the workstation, there is no need to judge the above date and time, so the schema information is obtained from the database server and the schema deployment area 221
, 321.

[0024] Through the above operations, the schema information (local schema) deployed on the workstation is guaranteed to be identical to the schema structure managed by the database server, and the workstation refers to its own local schema to access the database server. It is possible to create a program to access the system, and there is no need to modify the created program even if there is a change in the schema structure managed by the database server.

[0025]

[Effects of the Invention] As explained above, according to the present invention,
The schema structure managed in the schema structure management area of the external storage device of the database server is expanded to the schema expansion area provided on the external storage device of the workstation, so that each workstation can independently refer to this as a local schema. Make it. A workstation program that accesses a database in a database server refers to its own local schema to recognize the schema structure of the database.

[0026] Furthermore, when the schema structure of the database is changed, the date and time of the change is inquired of the database and compared with the date of its own local schema. If the date is also new, the schema information is retrieved from the database server and the local schema is rebuilt. This ensures the identity of the database schema structure and local schema, and each workstation can refer to the local schema deployed on its own external storage device, independent of the schema structure managed by the database server. It becomes possible to create a program that accesses a database server.

[0027] Through the above operations, according to the present invention, the identity of the schema information (local schema) deployed on the workstation and the schema structure managed by the database server is guaranteed, and the workstation refers to its own local schema. This allows you to create a program that accesses a database server, and there is no need to modify the created program even if the schema structure managed by the database server changes.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of a network system to which an embodiment of a schema structure management method according to the present invention is applied.

FIG. 2 is a flowchart illustrating a schema expansion operation when a workstation rebuilds its local schema in accordance with the present invention.

FIG. 3 is an explanatory diagram of a schema structure management method according to the prior art.

[Explanation of symbols]

1 Database server 11 CPU 121 Schema structure management area 2,3 Workstation 221, 321 Local schema development area

Claims (1)

[Claims] 1. In an information processing system in which a plurality of workstations and a database server are connected via a network and the database server is shared by the plurality of workstations, a schema development area is provided in an external storage device of the workstation, The schema structure managed in the external storage device of the database server is expanded into a schema expansion area provided in the external storage device of the workstation as a local schema that guarantees identity with the schema structure, and the workstation A schema structure management method characterized in that a program can be created independently of the schema structure of the database server by referring to a local schema.