JP2000187603A - System and device for supporting data base design/ maintenance - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the man-hour of work of system designer and RDB manager by changing change sports distributed over plural RDB corresponding to the change spots at the time of designing/maintaining a system composed of plural RDB while using a unified ER model. SOLUTION: A work 315 for change message storage is provided as an area for managing the processing state of a change request message transmitted to a DBMS. Then, an ER model change processing part 311 and an ER change message processing part 314 transmit the data of the work 315 for change message storage prepared based on respective information in an ER change request table 313 and ER model definition information 312 to the RDB as a message. Based on the received change message, a DBMS 61 changes RDB definition information 7. By performing processing while utilizing such respective definition information, the RDB definition information in the case of generating a change in the ER model definition information 312 can be simultaneously changed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a data model and a table mounted on a DB at the time of designing and maintaining a system centered on the data model when the data model is mounted on a plurality of distributed DBs. And a method of maintaining consistency between them.

[0002]

2. Description of the Related Art A conventional database design support technology is disclosed in Japanese Patent Application Laid-Open No. 7-325835. For example, based on information expressed in a data model (ER model) created by analysis in advance, a function of generating a database search sentence by designating by a user.
It was not a function to support the design of B.

Further, as a technology for supporting the design of a system realized by the RDB, a forward (ER) function is provided as a function of linking the ER modeling support tool and the RDB.
Model → Generate RDB definition) / Reverse (RDB definition →
(Generation of ER model) An engineering function is known, but the forward / reverse engineering function does not have a function of supporting data linkage between ER model definition information and a plurality of RDBs. For this reason, when one system is realized by a plurality of RDBs, a change occurs in the ER model during system design and maintenance, and the change is performed by a plurality of RDs.
In the case of B, it is necessary to manually perform the work of identifying the location to be changed and changing each RDB definition information in which the location that needs to be implemented is implemented. It could not be reflected in the RDB definition information.

As existing techniques for maintaining data consistency between RDBs, techniques for maintaining consistency between data stored in tables, such as two-phase commit and replication, have been realized. But
There has been no technique for maintaining consistency between the ER model and RDB definition information when changing distributed RDB design information at the RDB design / maintenance stage.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to design and maintain a system realized by a plurality of RDBs using a unified ER model. Multiple Rs corresponding to changes
The number of work steps of the system designer and the RDB administrator can be reduced by changing the change portion distributed to the DB.

[0006]

According to the present invention, as a means for solving the above-mentioned problems, an ER definition changing process for changing ER model definition information (312) inputted to a conventional ER modeling support tool is performed. Unit (311), an ER change request table (313) for storing a change request for ER model definition information, and E having a message transmission / reception function.
The R change message processing unit (314) is provided with a change message storage work (315) as an area for managing the processing state of the change request message transmitted to the DBMS. The ER model definition information (312) includes entity information (3121), entity / table correspondence information (3123),
Reference constraint correspondence information (3122) is included.

ER model change processing unit (311) and ER
The change message processing unit (314) transmits the data of the change message storage work (315) created based on each information in the ER change request table (313) and the ER model definition information (312) as a message to the RDB. Then, the DBMS (61) changes the RDB definition information (7) based on the received change message.

[0008] By performing processing according to the procedure using the above-described definition information, it becomes possible to change the RDB definition information in a batch when the ER model definition information (312) is changed.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a configuration diagram of hardware and a program of a computer to which the present invention is applied. The display device (1) is a device for displaying information of ER model definition information (312) managed by the ER modeling support tool (31) to a computer user. Input device (2)
Is the ER model definition information (3) displayed on the display device (1).
This is a device for inputting an instruction to the ER modeling support tool (31) for a change request when the computer user changes the content of 12). The processing device (3) is an electronic computer for executing the ER modeling support tool (31).

The ER definition change processing unit (311) receives a change request input from the input device (2) and a change message of the RDB definition information (7) received via the ER change message processing unit (314). , Based on the contents of the ER model definition information (312), a process for specifying a changed portion occurring in the ER model is performed, and the changed portion is recorded as a change request in the ER change request table (313), and the change request is recorded. ER change message processing unit (314). The ER model definition information (312) is a storage area for storing the definition information of the ER model.
121), entity / table correspondence information (3123), and reference constraint correspondence information (3122).

When the change message processing unit (314) is notified by the ER definition change processing unit (311) that a change request to the ER definition information (312) has been issued, the ER model definition information (312) and the ER Change request table (31
RDB definition information (7) to be performed based on the data recorded in 3) to prevent inconsistency between the ER model definition information (312) and the RDB definition information (7).
For creating a change message for transmitting the change of the RDB definition information to the DBMS (61) as a change request, and recording the created change message as a change request for the RDB definition information (7) in the change message storage work area (315). With.

FIG. 2 is a conceptual diagram taking as an example an ER model taken up in the embodiment and a case where the ER model is realized in RDBs on a plurality of processing devices. Also,
The data example in each figure after FIG. 3 is the ER model in FIG.
ER model is processed by processing device a (81), processing device b (82)
Based on the example realized in

FIG. 3 shows the entity information (3121) of the embodiment.
FIG. 4 is a data configuration diagram of FIG. The entity information (3121) is an area for storing data on each entity information among the information expressed in the ER model.

FIG. 4 is a data configuration diagram of the entity / table correspondence information (3123) according to the embodiment. In the case where the entity appearing in the ER model is actually constructed as a table in the RDB, the relationship between the entity and the table is shown. The correspondence is shown.

FIG. 5 shows reference constraint correspondence information (3
FIG. 122 is a data configuration diagram of FIG. 122), illustrating a data configuration when a reference key in the ER model is defined on the RDB as a reference constraint.

FIG. 6 is a data configuration diagram of the ER change request table (313) of the embodiment.

FIG. 7 shows combinations of values that can be taken by data in the change content column of the ER change request table (313) of the embodiment.

FIG. 8 is a diagram showing the data structure of a work (315) for storing a change message according to the embodiment. When a change request shown in FIG. 6 occurs, the ER change message processing unit (314) stores the change message. The content of the change message recorded on the work (315) is shown.

FIG. 9 shows combinations of values that can be taken by data of the ER change message storage work (315) of the embodiment. The data values in the figure are almost the same as those in FIG. 7, and the difference is that the “entity” in FIG.
The point is that it has been replaced with a “table” that is conscious of

FIG. 10 is a flowchart showing the flow of the entire process when an instruction to change the ER model definition information (312) is input from the input device in the embodiment.

FIG. 11 shows an ER modeling support tool (3) when an instruction to change the ER model definition information (312) is input from the input device (2) in the embodiment.
It is a flowchart which shows the process of 1).

In this embodiment, a change instruction is input from the input device (2), and the ER of the ER modeling support tool (31) is changed.
The process of changing the item name of the item “c2” of the entity C (802) in the model definition information (312) to “c2 ′” will be described below along the flow of the flowchart as an example. As a prerequisite to show an example,
ER modeling support tool (3
Consider cooperation between 1) and DBMS (61). The ER modeling support tool (31) is a program used when performing system design / development based on an ER (entity relation: entity relation) model, and edits, displays, and displays an ER model as a diagram. Has a function to support recording. The entity indicates a person, an object, an event, and the like handled in the business, such as “employee”, “product”, and “order”.

The ER model refers to a relational structure between entities, and the ER model is usually represented using an ER diagram.
In the initial state of the present embodiment, ER model definition information (312) in the ER modeling support tool (31) stores ER model (80) definition information and DB definition information. The system definition information stored in the ER model (80) stores the contents shown in the conceptual diagram of FIG.

In FIG. 2, a system component for systematizing a certain business is an entity A (80) as an ER model.
1), entity B (803), entity C (802), entity D
(804), which indicates that each entity is represented as an associated model. In the processing device a (81),
Entity A (801) represented in the ER model (80),
The entity B (803) and the entity C (802) are implemented as tables Aa (811), tables Ba (812), and tables Ca (813) in a state where the associations are held, respectively, and the processing device b (82) Then, the ER model (8
0), entity C (802), entity D (80
4) are table Cb (821) and table D, respectively.
b (822) indicates that the association is realized in a state where the association is held.

In the conceptual diagram of FIG. 2, an ER model (80) is recorded in ER model definition information (312) in FIG.
The table Aa (81) realized on the processing device a (81)
1), table Ba (812), table Ca (81)
3) is constructed as table definition information in the RDB definition information (7) connected to the processing device (6). A table Cb (821) and a table Db (822) realized on the processing device b (82) are managed by a DBMS on a processing device connected to a network corresponding to the two processing devices (6) in FIG. It is constructed as definition information in the RDB definition information to be performed.

Further, as shown in the respective entities described in the ER model and their relations, during the operation of the system, the data in the table realized in the processor a (81) and the data in the processor b (82) ) Indicates that the data in the table implemented in association with the application to ensure that it functions as one system in cooperation. The ER model definition information (312) includes entity information (3121), entity / table correspondence information (3123), and reference constraint correspondence information (312).
2), and the definition information of the ER model (80) is stored in the data configuration shown in FIGS.

The following is a description according to the processing flow of the embodiment of the present invention shown in FIG.

First, the procedure user inputs E from the input device (2).
When a request to change the item “c2” of the entity C (802) of the R model (80) to the item name “c2 ′” is input, the ER definition change processing unit (311) receives the change information.
(901) Next, in the procedure of the present invention, the ER definition change processing unit (31)
1) is based on the entity information (312) shown in FIG.
The data in 1) is searched, and for the requested change, the relevant change portion is specified and written to the change request table.
(902) The detailed procedure of the process of 902 will be described with reference to the flowchart shown in FIG.

The input change request is entity C (802).
Is changed to “c2 ′”. First, the ER definition change processing unit (311) includes entity information (3121), entity / table correspondence information (3123),
Based on the contents of the referential constraint correspondence information (3122), a change location that occurs in connection with the change request is specified in the change request table (3122).
Write to 13). (1001) When creating data to be written to the change request table (313) from the change request, the ER definition change processing unit (311) refers to the entity information (3121). Entity information (312
1) stores information on each entity in the ER model (80) shown in the conceptual diagram of FIG. 2, and the entity B (803) in the data configuration of the entity information (3121) shown in FIG.
From the information of item (a), the item constituting entity B (803) is "a
1 "," a2 "," c1 "," c2 "," b1 "...
“Bn”, “a1”, “a2”, “c1”, “c”
2 "constitutes the primary key of entity B (803).

A primary key attribute flag is set in an item constituting the primary key, and the flag is set to a symbol "K" in the data configuration.
Indicated by. Further, “a1”, “a2” and “b”
“1” and “b2” constitute “reference constraint 1” and “reference constraint 2”, respectively. The entity referred to by the item of “reference constraint 1” is entity A (801) and the item of “reference constraint 2”. Indicates that the entity referred to is entity C (802).
Reference constraint numbers in this table are numbers for identifying each reference constraint, and are defined to describe a set of items constituting the reference constraint. For example, in the data configuration, the item “a” described in the entity configuration item column of “entity B”
“1” and “a2” indicate that the number described in the reference constraint number column is a reference constraint of “1”, and a series of numbers are assigned to this reference constraint number from the top of the table in the figure. Have been.

Since the content of the change request is a change in the name of the item "c2" of the entity C (802), the range of influence that occurs in connection with the requested change is the entity information (31) shown in FIG.
From the data structure of 21), the item “c” of the entity C (802)
2 ", item" c2 "of entity B (803) (reference destination entity is entity C (803)), item" c2 "of entity D (804) (reference destination entity is entity C (802)) Is written in the ER change request table 313. The ER change request table (31)
The data written in 3) has the data configuration shown in FIG.

The “target type” column in FIG. 6 indicates the type of the target of the change request, and includes “substance”, “item”, “primary key”,
A value for identifying one of the change requests of “reference constraint” is recorded. The “change type” column indicates what kind of change the change request for the “target type” includes,
A value for identifying either “update” or “delete” is entered. The “content type” column indicates which content of the attribute of the data item is changed or updated when the value described in the “target type” column is “item.” The description format of the column is determined by the value recorded in the "content type" column as shown in Fig. 7. In the format shown in Fig. 7, when the entity is deleted, the value is set to "object type". The “entity” is recorded, the value “deletion” is recorded in the “change type”, the value is not recorded in the “content type”, and the “entity name” to be deleted is recorded in the “change content” column. Similarly, in the case of deleting the primary key, the value “primary key” is set in “target type”, the value “delete” is set in “change type”,
No value is recorded in “content type”, and no value is recorded in “change content”. The reason why "change content" is not particularly entered in the primary key is that the primary key does not have a unique name.

Further, when deleting a referential constraint,
The value “reference constraint” is recorded in “target type”, the value “delete” is recorded in “change type”, the value is not recorded in “content type”, and the “reference constraint number” is recorded in “change content”. Be recorded.

There are three types of changes to an item: "delete", "add", and "update". For "delete" and "add", the item itself is changed and the item is used as the primary key. There is a change to be set and a change to set an item as a reference key. Also, regarding the "update" of an item, only the change of the name, type, and number of digits constituting the item is allowed, and the change of "primary key" and "reference constraint" is performed by "delete" and "addition". .

Further, the combination of values in the data configuration diagram does not describe the combination of values in the case of creating an entity, in the case of creating a new primary key, and in the case of adding a referential constraint. Substitute for adding an item, adding a primary key to an item, and setting a referential constraint to an item, respectively. If one of the data structures in FIG. 7 is described as an example, "object type"-
"Item", "Change type"-"Add", "Content type"-
The "change contents" in the case of "referential constraint" is "referential constraint number, item name, order in referential constraint". When a certain item in the entity is incorporated into referential constraint, which referential constraint should be included? (“Reference constraint number”), which item to incorporate (“item name”), and where to incorporate it in the referential constraint (“order within referential constraint”)
This indicates that the information is to be recorded in the "change contents" column.

Next, an ER message processing unit (314)
Refers to the "target type" and "content type" columns in the data configuration of the ER change request table (313), and checks whether the change request is for a reference constraint. (1
002) Here, from the data configuration shown in FIG. 6, “change request” is for “item”, “change type” is “update”, and “content type” indicating the update content is “name”. From this, it can be seen that the change request is a change in the name of the item. (1003) Next, the ER change message processing unit (314) refers to the contents of the entity / table correspondence information (3123) shown in FIG. 4 and checks the data configuration of the ER change request table (313) shown in FIG. The “entity name” is replaced with the actual device name and written in the change message storage work (3122).
(1004) In the data example in FIG. 4, a “table name” corresponding to an entity required when the entity is realized as a table, a “DB name” defining the table, and a DBMS for managing the DB Information such as “device name” to be executed, and entity / table correspondence information (31
By having the data shown in 23), it is possible to grasp the correspondence between the entity and the table even when the entity in the ER model is realized in the RDB on a different device.

The data values of "1" and "2" in the "message number" column shown in the example of FIG. 4 are numbers given by the ER change message processing unit (314) when writing a change message. A series of numbers for uniquely identifying each message in the configuration. The ER change message processing unit (314) assigns a “message number” and simultaneously identifies the original change request. “Change process number” is assigned. Since the "change process number" assigns a set of numbers to a change generated by one change instruction, all the change messages of the data configuration in FIG. 8 have the "change number" of "1". Immediately after a new change message is created from the ER change request table (313), the “change state” of all the change messages is set to “not transmitted”.

The above is an example of the change of the item name. In the case of the change of the reference constraint, the reference constraint correspondence information (31) shown in FIG.
22), referencing the data of FIG.
The content replaced with the reference constraint name defined in B is written to the change message storage work (3122). (1
In the data configuration of FIG. 5, the reference constraint with reference constraint number “1” of entity B (803) to entity A (801) is changed from table Ba (812) to table Aa (81).
1) is defined as "reference constraint 1a" to entity 1 (1), and entity B (802) to entity C (80
The reference constraint to 3) is the reference constraint number “1” is the table Ba.
(812) is defined as “reference constraint 2a” from the table Ca (813).

Here, the reason why the reference constraint with reference constraint number "1" is implemented as "reference constraint 1a" and the reference constraint with reference constraint number 2 is implemented as "reference constraint 2a" will be described. ER
The reference constraint on the model is managed only as a set of items identified by a number (reference constraint number is “1”), but when realized in an RDB, a constraint having a unique definition name on the RDB In this data configuration example, the unique names of the RDBs are illustrated as “reference constraint 1a” and “reference constraint 2a”.

The data example in FIG. 8 shows the contents of the change to the RDB that occurs when the name of the item “c2” in the entity C (803) is changed to “c2 ′”. The change message processing unit (314) stores the contents of the work (315) for storing a change message in the table "C813" corresponding to the entity C (803), the table Cb (821), and the item "c2" of the entity C (803). Table B referring to "
a (812) and a change of the table Db (822). In addition, 1001 to 1005
The data shown in FIG. 8 created by the procedure described in FIG. 8 is the entity information (3121), entity
Table correspondence information (3123), referential constraint correspondence information (3
122), and is created based on the data values in the change request table (313).

In the "change state" column of FIG. 8, 5 is set to have both the message transmission state and the RDB change state.
The type value is recorded. The meaning of each data value is as follows: “unsent” indicates that the message has not been sent, “sent” indicates that the message has been sent, and “changed” indicates the RDB of the sent message. The state in which the change is completed, “determined” indicates a state in which an instruction to determine the change of the RDB has been transmitted, and “determination completed” indicates the RDB change confirmed state. RDB immediately after the end of RDB change
Can be canceled to return to the state before the change (rollback), and if the change of the RDB is confirmed after the change of the RDB, the state of the RDB cannot be returned to the state before the change.

By having these “changed” and “completed” states, when the ER model is implemented by a plurality of RDBs, all changes in the plurality of RDBs become “changed”.
After confirming that the update has been performed normally, it is possible to perform a process of transmitting an instruction for confirming the change to each RDB, and all RDBs are in a state in which consistency with the ER model has been obtained. Guarantee.

Further, the data configuration of FIG. 8 is in accordance with a combination of values that can be taken by the data shown in FIG. In the value combinations, when creating a table, when creating a new primary key, when adding a referential constraint, the value pairs for each are not described. Substitute by adding a primary key to the item and setting a referential constraint to the item.

According to the present invention, according to the procedure described above,
A change request message for changing RDB definition information when an ER model change request occurs can be created.

A procedure for reflecting the change in the ER model in the RDB definition information based on the created change request message will be described below with reference to the flow of the embodiment shown in FIG.

Next, the ER message change processing unit (31)
4) sends the contents of the change message storage work (3122) to each RDB. As shown in FIG. 2, since the ER model (80) is stored in the RDBs of two different processing devices a (81) and b (82), the change message storage work area (315) shown in FIG. ) Is a table Ca corresponding to the entity C (802).
(813) indicates that a change to the item of the table Cb (821) occurs. In this example, the message number “1” and the message number “3” of the data shown in FIG.
Is transmitted to the processing device a (81), and the message with the message number “2” and the message number “4” is transmitted to the “processing device b (82)”. After the transmission, the “change state” of the work for storing a change message (3122) is rewritten to “transmitted”.

Processing unit a (81), processing unit b (82)
The DB change message processing unit (611) of the DBMS (61) operating on each of the R and R messages is transmitted based on the message transmitted from the ER change message processing unit (314).
Change the DB definition information (7). The DB change message processing unit (611) of the DBMS (61) operating on the processing device a (81) transmits the message number “1”,
The “change state” of the message “3” is rewritten to “changed” and returned to the ER change message processing unit (314). DBMS (61) operating on processing device b (82)
The DB change message processing unit (611) rewrites the “change state” of the transmitted message with the message numbers “2” and “4” to “changed” and returns it to the ER change message processing unit (314). (903) Next, the ER change message processing unit (314) of the ER modeling support tool (31) includes the processing devices a (81) and b
RD of DBMS (61) operating on each of (82)
A change message in which the "change status" is rewritten as "changed" is received from the B change message processing unit (611). The ER change message processing unit (314) receives the replies of all the change messages, and confirms that all the "change states" of the change messages are "changed". After confirmation, a message instructing confirmation (commit) of the change is transmitted to the RDB change message processing unit (611) of the DBMS (61) operating in each of the processing devices a (81) and b (82).

The RDB change message processing unit (611) of each of the processing devices a (81) and b (82) receives an instruction message for confirming the change from the ER modeling support tool (31) and receives the DB definition change processing unit (611). 612) confirms the change (commit). Processing device a (81), 2
(82) Each RDB change message (611)
Rewrites the “change state” of the change message to “completed” after the determination is completed, and returns it to the ER change message processing unit (314) of the ER modeling support tool (31). (905) Next, the ER change message processing unit (314) receives, from the processing devices a (81) and b (82), a reply of a change message indicating that the change has been confirmed, and for the change message for which the determination has been completed, the change message. Work for storage (31
The “change state” of 5) is set to “completion completed”. After the "change status" of all the change messages in the change message storage work (315) becomes "confirmed",
The ER definition change processing unit (311) executes the ER definition information (31)
The contents of 2) are changed according to the contents of the ER change request table (313). (904) As described above, according to the present invention, a change message is written in the change message storage work (315) based on the ER model definition information (312) according to the procedures shown in FIGS. By transmitting to the DBMS (61), it is possible to reflect the change of the ER model in the RDB definition information.

[0050]

As described above, according to the present invention, in the design and maintenance of a system, system design information realized in a plurality of RDBs is managed by a unified ER model,
By reflecting the change in the R model on a plurality of RDBs, the burden on the RDB administrator and the system designer can be reduced. Similarly, when one RDB definition information is changed, the RDB change information can be reflected in the entire system via the ER model.
The possibility of inconsistency with the system design information due to the local change of the DB can be reduced.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of hardware and a program of a computer according to an embodiment of the present invention.

FIG. 2 shows an ER model of the embodiment and a plurality of RDBs.
It is a conceptual diagram in the case of storing in.

FIG. 3 is a data configuration diagram of entity information (3121) of the embodiment.

FIG. 4 is an entity / table correspondence information (312) according to the embodiment;
It is a data structure figure of 3).

FIG. 5 is a data configuration diagram of reference constraint correspondence information (3122) of the embodiment.

FIG. 6 is a data configuration diagram of an ER change request table (313) of the embodiment.

FIG. 7 is a diagram showing combinations of values that can be taken by data of the ER change request table (313) of the embodiment.

FIG. 8 is a data configuration diagram of a change message storage work area (315) according to the embodiment.

FIG. 9 is a diagram illustrating combinations of values that can be taken by data of the ER change request table 315 according to the embodiment.

FIG. 10 is a flowchart illustrating a flow of an entire process when an instruction to change ER model definition information (312) is input from the input device in the embodiment.

FIG. 11 shows an embodiment in which the input device (2) transmits the ER
E when change of model definition information (312) is instructed
It is a flowchart which shows the flow of a process of the R modeling support tool (31).

[Explanation of symbols]

1 ... A device connected to the processing device (3) for displaying ER model definition information, 2 ... A device connected to the processing device (3) to input a request for changing the ER model definition information,
... Processing device for executing the ER modeling support tool, 31 ... ER modeling support tool, 311 ... ER
Definition change processing unit, 312... Storage area for storing ER model definition information, 3121... Storage area for storing entity information, 3122... Storage area for storing reference constraint correspondence information, 3123. Storage area for storing correspondence information, 313 ... Storage area for storing ER model change request, 314 ... ER change message processing unit, 315 ... Work area for storing ER change message, 6 ... Relational database management system ( Device for executing DBMS), 61 ... Relational database management system (DBMS), 61
1 ... RDB change message processing unit, 612 ... RDB definition information change processing unit, 7 ... Device connected to the processing device (6) for storing information that defines the structure of a relational database (RDB).

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Etsushi Oku 2-chome, Kagahara, Tsuzuki-ku, Yokohama-shi, Kanagawa Prefecture F-term in the System Development Division, Hitachi, Ltd. 5B082 BA09 GA07 GA15

Claims (1)

[Claims] 1. A system for supporting system design and maintenance when a system represented as a data model is distributed and implemented in a plurality of DBs connected via a network, wherein a data model is included in data model definition information. With table information implemented on the DB,
In addition, each of the data model definition information management function and the DBMS function has a message processing unit, and when the definition information of the data model is changed, investigates the influence of the change based on the definition information of the data model, and is under the influence of the change. A database design / maintenance support method and apparatus for maintaining consistency between data models and definition information of a plurality of DBs that implements the data model as a table by changing definition information of the plurality of DBs.