Terms of Reference, Conceptual Model, Fragmentation...

Terms of Reference

For the execution of design work, specialists are required in accordance with the staffing table. If there are vacant seats, applicants are selected on the basis of personal data.

It is necessary to design - in order to help the leader - the corresponding expert system of real time. It is assumed that the selection of scientific employees is carried out by the scientific division of the firm, and the engineering staff is the production unit.

The volume of the database does not exceed 1 GB.

It is necessary to use a widely used DBMS. The database interface should be counted on the end user (CP) of the entry level, that is, the knowledge of high-level programming languages ​​is not required from the CP.

The database must have recovery capabilities in case of failures and have sufficient speed.

Conceptual model

Based on TK, you can create a set of database tables. Table Rules is given earlier. In the tables Staff Schedule (Table 15.2) and the "Worklist" section. (Table 15.3), data is given only for the first cycle.

Table 15.2

Staffing (primary)

Time

Position

Plan

Fact

Jobs

1

Researcher

10

5

5

1

Design Engineer

9

7

2

1

Operations Engineer

12

9

3

Database Procedure

Fig. 15.2. Procedure for working with DB: P - accepted; B - vacancies

Table 15.3

List of staffing tables (primary)

Time

Last name

Academic degree

Discoveries

Average Score

Experience

Status

Position

1

Vodopyanov

Yes

Yes

4.8

7

Works.

Науч. Comp.

1

Karimov

Yes

Yes

3.3

5

Works.

Науч. Comp.

1

Kramskoy

Yes

Yes

4.2

8

Works.

Науч. Comp.

1

Screamers

Yes

Yes

3.5

9

Works.

Науч. Comp.

1

Trubetskov

Yes

Yes

4.1

15

Works.

Науч. Comp.

1

Krymov

Yes

No

4.0

4

Works.

Ing.-cons.

1

Mamedov

Yes

No

3.9

6

Works.

Ing.-cons.

1

Orlov

Yes

No

3.7

3

Works.

Ing.-cons.

1

Sintsov

Yes

No

4.5

1

Works.

Ing.-cons.

I

Petrovich

Yes

No

4.2

7

Works.

Ing.-cons.

1

Cockroaches

Yes

No

4.1

3

Works.

Ing.-cons.

1

Travkin

Yes

No

5.0

9

Works.

Ing.-cons.

1

Khokhlov

Yes

No

4.0

4

Works.

Ing.-cons.

1

Cherkas

Yes

No

4.8

2

Works.

Ing.-cons.

1

Kasymov

Yes

No

3.3

3

Works.

Ing.-cons.

1

Contours

Yes

No

3.0

4

Works.

Ing.-cons.

1

Merchants

Yes

No

3.3

5

Works.

Ing .-

Operational

I

Rebroon

Yes

No

3.4

7

Works.

Ing .-

Operational

1

Remezov

Yes

No

3.4

5

Works.

Ing .-

Operational

1

Sokolov

Yes

No

3.3

3

Works.

Ing .-

Operational

1

Tiunov

Yes

No

3.0

6

Works.

Ing .-

Operational

1

Troekurov

Yes

No

3.0

4

Works.

Ing .-

Operational

1

Sorrel

Yes

No

3.2

9

Works.

Ing .-

Operational

1

Karpov

Yes

Yes

3.2

1

Pretend.

!

Krylov

Yes

Yes

3.1

2

Pretend.

1

Sintsov

Yes

No

4.5

1

Pretec.

!

Simonov

Yes

No

3.9

2

Pretend.

1

Ivanov

Yes

No

3.2

3

Pretend.

1

Goats

Yes

No

3.4

4

Pretend.

1

Petrov

Yes

Yes

4.0

1

Pretend.

1

Gurov

Yes

No

4.0

3

Pretend.

1

Flowers

Yes

No

3.0

1

Pretend.

Fragmentation and localization

From the terms of reference it follows that it is necessary to make a horizontal fragmentation of the tables, which is most convenient for introducing species. This option, regardless of the chosen DBMS, is simultaneously one of the ways to protect data from unauthorized access. Naturally, the database is located on the server. Duplicating the data is done by creating a backup.

DBMS selection

Stop the selection, as before, on the relational data model, as widely used.

It's easy to see that the database should be multi-user, which can be achieved by multi-user (file-server) mode or client-server mode. Preferably, due to less traffic, the client-server mode is.

As a criterion for selecting a particular DBMS in accordance with the TOR, the locking mechanism, data storage features, performance, installation nature, maintenance, configuration and configuration, data recovery in case of failures, resource requirements (see clause 14.4) can be used. see Table 14.1).

The above criteria are most satisfied by the InterBase database used in the Delphi environment.

Let's first give the basic limit characteristics of InterBase.

The volume of the database is 10 GB, the number of fields is up to 10,000, the number of entries is limited, the number of tables is up to 65,000, the length of the entry is up to 64 KB, the length of the field is up to 32 KB, the nesting of the SQL query is up to 16 , the size of the stored procedure or trigger - up to 48 kilobytes.

InterBase uses the following data types: small (± 32 767, 2 bytes); integer (± 2 billion; 4 bytes); float (+ 3,4 Е ± 38; 4 bytes); double precision (± 1,7 Е ± 308; 8 bytes); char, varchar (character type, up to 255 characters); date. Instead of the float data type, it's better to specify decimal ( a , b ) or numeric ( a , b ), where a - the number of characters; b is the number of decimal places.

Logical model. Due to the specifics of the tables, links between them, in the form of a link scheme, are not created. The necessary links are established in the corresponding requests.

thematic pictures

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