Centralized databases, Design of a centralized database, Terms of reference - Databases

Centralized databases

Designing a centralized database

Consider the database "Learning process".

Requirements analysis. The educational process is accompanied by a significant flow of information in the dean's office, which has been processed either manually or with minimal use of computer technology.

The difficulties of the processing process are determined by the fact that it must be done qualitatively (without errors) and in very short terms (the beginning and end of the fall semester, the end of the spring semester). Based on the results of processing, it is necessary not only to take information into account, to form a number of documents (certificates, statements), but also to work out solutions (prepare orders for expulsion, transfer of students to the next course).

The work of the dean's faculty is characterized by significant streams of documentary information linking the dean's office with virtually all departments of the institute.

One and the same information can be present in different documents. For example, the list of students is in the orders of the rector, in the test and examination sheets, in the lists of students subject to conscription, in the documents of the contract department, in the dean's orders.

Changing at least one data item can lead to the need for synchronous data changes in a number of documents.

Existing data processing with a time deficit is fraught with the following possible consequences.

1. Low speed of preparation of the necessary documentation due to the considerable laboriousness of the process.

2. Errors in completing documents due to time constraints. So, the process of entering ratings into the card for the implementation of the curriculum takes several days. The difference in the form (structure) of the card and the examination sheet as a source of primary information can lead to additional errors in the introduction of data.

3. Manual duplication of information elements in different documents of different departments can lead to disagreement in the same data (violation of data integrity).

What has been said allows us to conclude that it is necessary to build a computer database for the learning process.

To form the composition of the database fields, we will conduct a survey of the educational process (available workflow).

There are four chairs at the faculty, three of them are graduates. Students are divided into groups: for each graduating department, six groups are assigned.

The learning process is cyclical, and therefore it is enough to consider only one (annual) cycle, consisting of the fall and spring semesters.

At the end of the spring semester (April-May) of the school year, on the basis of the curriculum coming from the training department, the dean's office prepares the study schedules. They are actually corrected by the annual "clippings". from the five- or six-year plans of the relevant specialties. This is the main source of information about the composition of the learning process.

During the academic year, the dean's office organizes the implementation of the academic schedule by students and teachers.

At the end of the semesters (December-January, May-June), the deanate issues the statements (credits and exams) to which the teachers of the departments make assessments about examinations, credits, course projects (works). Received data is logged in the & quot; Execute Curriculum & quot; and in the & quot; Student's Student Card & quot ;.

Next, the processing of cards using the following algorithms begins.

1. Successful students are awarded a scholarship. The list of such students is transferred to the office (reception of the rector) and to the accounts department.

2. Students who have not liquidated debts (one or more unsatisfactory grades) are presented to the deduction. The relevant lists along with the draft order are transferred to the office and the commercial department.

3. Only in the spring semester, an order is being prepared to transfer successful students to the next course, the successful graduation from the university graduates and their expulsion from the institute.

Scheme & quot; manual & quot; information flows of the educational process is shown in Fig. 14.1.

Thus, a list of & quot; minimal & quot; necessary output documents (requests and reports).

Let's list the main ones.

1. Issuance of lists of students by groups (indicating the names of headmen).

2. Search for the names of students (in groups) who passed the session on an "excellent" basis, with one evaluation "good", with two grades "good", preparing and printing out the corresponding orders for the scholarship.

3. Formation of test scores.

4. Issuance of the list of teachers in the departments with indication of the subjects taught by them in this semester.

5. Formation at the end of the academic year of orders for transferring to succeeding students the next year and on assigning unsuccessful students (with the order and representation of the dean, respectively).

6. Issuance of a list of students liable for military service.

The system of columns (columns) of the database tables "The learning process" is revealed in two ways: as a result of conversations with the user and on a documentary basis (according to the nomenclature of dean's affairs).

Dean's Workflow

Fig. 14.1. Document management of the dean's office:

1 - personal files, orders for enrollment; 2 - number of groups, educational order; 3 - semester schedule; 4 - orders of the rector, orders of the dean's office, statements; 5 - lists, list of teachers, list of curators; 6 - draft orders for students, academic certificates, attachments to the diploma; 7 - the list of those paying for training, who changed the form of payment; 8 - the list of recruits, the list of those living in the hostel; 9 - orders for scholarships, deductions, various assistance forks; 10 - Rector's orders, academic certificates, supplement to the diploma; 11 - list of groups; 12 - lists of teachers; 13 - lists accepted for 2-6 courses

Due to a large nomenclature of documents, we select the main ones and classify them. Define four classes.

1. Documents originating in the dean's office and used there ( & internal documents ).

03. Regulations on the Faculty.

07. Instructions and orders of the dean.

16. Reports on the results of examinations and in-house certification.

22. Personal student cards (form 13).

23. Students' registration cards (form 14).

27. Journal of issuing student tickets and credit books.

2. Documents formed in the dean's office and transferred to other divisions.

08. Annual plan and report of the faculty on work in the academic year.

09. Calendar plan of the dean's office.

14. Statistical report on the movement of students for the academic year.

20. Materials on deductions.

24. Lists of students by study groups (form 18).

3. Documents , coming from other departments and used only in the dean's office.

04. Orders and instructions of the rector on main activities.

05. Orders and instructions of the rector on the staff of students.

17. Materials on industrial practice.

18. Examination and test records.

19. Journal of the results of examination sessions and attestations.

4. Documents coming from other units, processed in the dean's office and transferred to other units.

02. Typical and educational plans.

13. Load performance report.

15. Diploma projecting.

16. Examination and test records.

25. Schedule of training sessions and examination sessions.

The greatest interest for building a database is the case 02,

05, 07, 08, 13, 14, 16, 17, 20 and especially 22-25.

We show the procedures for processing information when using the database. For this, we detail Fig. 14.1 and obtain Fig. 14.2. The algorithm for applying this figure is detailed in Fig. 14.3. It is followed by three algorithms for processing information.

Algorithm A.1. List students who passed the session only on & quot; excellent & quot ;. Determine the list of students who passed the session not lower than "good". Draw up draft orders for higher and ordinary scholarships.

Algorithm A.2. Make a list of students who have at least one rating & quot; unsatisfactory & quot ;. Form a draft order for deduction.

Algorithm A.3. Make a list of students who do not have any unsatisfactory grade. Submit the draft order for transfer to the next course.

Based on the submitted information on the document flow, we will form the basic requirements for the database in the form of a technical assignment.

Scheme of main information flows

Fig. 14.2. Scheme of the main information flows (see figure 14.1 for designations)

Terms of Reference

You should submit such general requirements to the database being created.

1. The database should be designed for a non-professional user in programming.

2. The database should be built on the basis of a widely used DBMS.

3. The volume of the database will gradually increase and at the initial stage will not exceed 1 GB.

4. The database must have a convenient interface.

5. The database should provide for the possibility of queries of arbitrary structure when working with the database in the workplace.

6. The database contains exhaustive data about students.

Detailed flow of information flows

Fig. 14.3. Detailed flow of information flows.

The notation is the same as in Fig. 14.1. and 14.2

It is necessary to provide for the protection of information. Data for the database is provided by the customer.

In the database, the first stage should include the following tables, forms and reports.

Tables and their fields are listed later in the form of a link diagram.

In each table in the first stage there must be at least 10 entries entered by the performer. Provide for entering records directly into tables or using appropriate forms.

Reports

Statement.

Group.

Teacher.

Student.

Military liable list.

Order for transfer.

Session results.

Debtors.

Excellent.

Forms

Subject:

Group of students.

Chair-teacher.

Specialty.

Learning subjects.

Performance.

The main button form.

Once a year, you need to change a series of data (group name, course number) in semi-automatic mode. The sixth course in this case becomes for one year as a seventh course.

Data about graduates ("groups of the 7th year") should be stored in the database within one year. In addition, data on earlier releases should be kept. The frequency of access to these archived data is much lower than to the "working" quot; information. At the same time, these data can unnecessarily load the database, reducing its performance. In order to avoid such an undesirable effect, it is better to transfer archival data in a semi-automatic mode to another, archival database, which in the theory of databases has been called the "data store."

Much of the data for the database "The learning process" contained in the database "Entrant" should be read from there in semi-automatic mode. At least the bulk of the data should come from curricula and graphs. With the laborious manual input of such information, many errors can arise. To reduce their number, it would be necessary to automate the process of drawing up these plans and graphs, providing for a semi-automatic process of entering information into the database "Training process".

It is necessary to provide automatic counting of some characteristics (for example, the number of students in the group after the changes in it - allocations or adding students to the group).

For expelled students, you should probably create a special spreadsheet, where you automatically transfer data when the student is expelled and & quot; return & quot; this data when it is restored. Perhaps the same option should be provided for students on academic leave.

The retention of data about the retired teachers is held in the archival database.

TK serves as the basis for the work at subsequent stages.

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