JPH0344332B2 - - Google Patents

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention adds a control data item to the beginning of a record having a plurality of data item groups, and checks whether the contents of each data item group are valid in the control data item. The present invention relates to a control method for variable records that writes control data indicating whether or not the data is valid, thereby preventing data groups whose contents are meaningless from being stored in a database.

[Conventional technology and problems]

Figures 1 to 3 are diagrams for explaining problems in the prior art. In Figures 1 to 3, A to C are records, α and β are sets, and a
thru c indicate actual values, X indicates a record combining A through C, and x ₁ through x ₃ indicate actual values, respectively. Now, as shown in FIG. 1, assume that data item groups indicated by A, B, and C are stored or retrieved between an application program and a database. When performing the above-described processing in a network database, logical structures as shown in FIGS. 2 and 3 can be considered. In the case of FIG. 2, the presence or absence of record C (or record B) can be controlled based on the conditions of the actual values (α ₁ , . . . ) of record A, so space efficiency on the database is good. However, it is necessary to issue DML (Database Manipulation Language) for storage/retrieval keeping the sets α and β in mind, which poses a problem in terms of processing efficiency. In the case of FIG. 3, record X is a combination of formats A to C, and data item groups B and C exist regardless of the actual value of data item group A. Therefore, although the processing efficiency is good, there is a problem in terms of space efficiency.

[Purpose of the invention]

The present invention is based on the above considerations, and includes:
The object of the present invention is to provide a variable record control method that allows efficient database access and improves database space efficiency.

[Structure of the invention]

For this reason, the variable record control method of the present invention allows records stored in the application program work area that communicates between the application program and the database management system to include all predefined data item groups and each data item group. It consists of a control data item that has a value indicating whether a group of items is meaningless (null), and records stored on the database are controlled by a record control section, the control data item, This feature is characterized in that it consists of a group of data items (having a value that is not the same).

[Embodiments of the invention]

FIG. 4 is a diagram showing the principle of the present invention, and FIG. 5 is a diagram showing means for storing records in a database.

As shown in FIG. 4, if the record type of record X is defined as having data item group A, data item group B, and data item group C, then UWA (user program work The record X on the area) contains control data item CTL, data item group A,
It has a data item group B and a data item group C. In the illustrated example, the control data item has a 3-bit configuration, the first control bit (first bit) corresponds to data item group A, and the second control bit corresponds to data item group B. However, the third control bit corresponds to data item group C. A control bit of logic ``1'' indicates that the contents of the corresponding data item group is meaningful (has a non-null value), and a control bit of logic ``0'' indicates that the contents of the corresponding data item group are meaningless. It shows. STORE is a macro instruction for storing records, MODIFY is a macro instruction for updating records, and GET is a macro instruction for retrieving records in a database. A record X of a database (abbreviated as DB) is composed of a record control section, a control data item, a data item group A, and a data item group C in the illustrated case. Record control information that associates records is written in the record control section, but in the illustrated example, record X has no relationship with other records, so it can be regarded as delimiter information (note that record There is no correlation with data item CTL). As can be seen from Figure 4, logic "0"
The data item group corresponding to the control bits does not exist in the data X on the database.

FIG. 5 shows a means for storing records in a database. In Figure 5, 1
is an application program, 2 is an analyzer, 3 is a schema/subschema, 4 is a STORE routine, 5 is a page input/output processing unit (hereinafter referred to as PIOC), 6 is a database, 7 is a page buffer, 8 is a
Each shows UWA. Also,,…
' indicates processing order, solid lines indicate control flow, and double lines indicate data flow. Schema/subschema 3 is a table expressing the structure of variable record X, and shows the correspondence between control bits and data item groups A, B, and C.
Note that the part existing between the application program 1 and the database 6 is a DBMS (Data Base
Management System).
When storing record X in database 6, application program 1 writes data item group A, data item group B, and data item group C forming record X on UWA 8, and writes control data items thereto.
Append CTL and issue a STORE macro instruction. The STORE macro instruction performs the following processing.

The STORE macro command issued by the application program 1 starts STORE processing via the analyzer 2 (distribution unit to each macro).

STORE routine 4 requests PIOC 5 to read page α of database 6.

' Page α on database 6 is page
It is read onto the buffer 7.

' STORE routine 4 refers to record X (including control data item CTL) on schema/subschema 3 and UAW 8, and stores data item group A and data item group C whose control bit is logic "1" in the page buffer. Transfer to page α above 7.

' The STORE routine requests the PIOC 5 to write page α to the database 6.

When a GET macro instruction is issued (not shown), the DBMS retrieves the record from the database and, if a logical "0" control bit is present, assigns a value indicating that the contents are meaningless to the corresponding data item. This data item is inserted into a predetermined position in the record read from the database, and transferred to the UWA 8.

〔Effect of the invention〕

As is clear from the above description, according to the present invention, it is possible to efficiently access a database and improve the space efficiency of the database.

[Brief explanation of drawings]

1 to 3 are diagrams for explaining the problems of the prior art, and FIG. 4 is a diagram illustrating the principle of the present invention.
FIG. 5 is a diagram showing means for storing records in a database. 1... Application program, 2... Analyzer, 3
...Schema/subschema, 4...STORE routine, 5...Page input/output processing unit (referred to as PIOC), 6...Database, 7...Page buffer, 8...UWA.

Claims (1)

[Claims] 1 Check whether records stored in the application program work area that communicates between the application program and the database management system include all predefined data item groups and whether each data item group is meaningless (null). A control data item with a value indicating , and a record stored in the database is made up of a record control section, the control data item above, and a group of meaningful data items (having a non-null value). A variable type record control method characterized by the following.