Building the database itself, Building the structure, Establishing...

Building the database itself

We describe the version of the technology for building tables within the Access database.

After opening the Access database and selecting the New Database radio button in the intermediate window, the New database file window opens. In it, you must specify the name of the database and its address. After clicking the Create button, the main Access DB window opens (see Figure 14.5), in which you select the Tables tab.

Constructing a structure

The structure of the table is easiest to create with the help of the constructor. To do this, click the Create Table in Design Mode button, and the main window for creating the table will appear on the screen (see Figure 14.6). List of fields in the database tables Academic process is given in Appendix 1.

Main Access DB Window

Fig. 14.5. Main Access DB window

At the top of the main window (tables), you specify the field names and the corresponding data types. The latter are selected from the combo box. In the field Description of the window it is possible to give a brief description of the table fields.

In the lower part of the main window, the table properties (data type parameters, initial values, conditions for values) can be set, index fields are entered, the condition of mandatory filling of the table field is specified.

Primary key fields, which it is desirable to place first in the structure, are marked (using the Ctrl key if there are several fields), and then on the toolbar, click the icon with the key image. The key symbols appear in the corresponding fields in the field description of the top part of the main window.

After the structure of the table has been formed, the main window is closed (the "x" icon in the upper right corner). The computer in the additional pop-up window asks you to enter the name of the table (suggesting by default the name TABLE, where i is the serial number) or refuse to save the result.

Main window for creating tables

Fig. 14.6. The main window for creating tables

After entering the table name (for example, the "Group") and pressing the Yes button of the additional pop-up window, this window is closed and the table name appears in the list of tables in the Tables tab of the main window Access DBMS.

The structure of all tables is formed by the described method.

Establishing links

To create a connection scheme, click the Data Schema button on the Access toolbar (in the main window on the Tables - tab in Figure 14.5), the main window , shown in Fig. 14.7.

Additional data schema window

Fig. 14.7. Additional data schema window

In the pop-up additional window, select the necessary tables and add them to the main window, after which the additional window is closed.

Next, you establish links from the parent key to the foreign key (for example, "Group. Group number", "Student. Group number"). To do this, select the parent key, click the left mouse button and, without releasing it, drag the cursor to the external key. A new additional window appears (see Figure 14.8), in which the communication fields are indicated. To ensure referential integrity, click the checkboxes Ensure data integrity, Cascade update, Cascade delete.

New additional data schema window

Fig. 14.8. New additional data schema window

After the additional window is closed, a corresponding link appears in the main data schema window.

Other connections are established in a similar way. As a result, the scheme shown in Fig. 14.9 and characterizing the results of the normal loan.

Filling

Initially (see Figure 14.9), the tables "Chair", "Subject", "Enterprise" should be filled. Secondly, fill out the tables "Laboratory", "Specialty", "Teacher", "Bank of vacancies". After that the table "Group" can be filled. Next, go to the Student and "Study". Then comes the turn of the tables "Profitability", "IPP", "Payment", "Hostel", "Order". Finally, the table "Order type and Attestation & quot ;.

You can fill in the following ways:

• Directly entering data into a table;

• through the form object;

• from other databases;

• from other tables in this database using calculations and queries.

The first two methods are preferred when introducing a small amount of data. Tables are best used when filling out and then viewing the data.

More convenient is the interactive introduction of data through the forms listed in the ToR.

Let's show the formation of the form Group based on the same name table.

In the main DBMS window, go to the Forms tab and click the Create a form with the wizard. In the first Wizards window that opens, select the table and its fields, which should be placed in the form. In the subsequent windows, choose the appearance, style of the form. In the last window of the Wizards , specify the name of the form (by default or after the adjustment). Clicking Finish completes the creation of the form whose name appears in the list of the main DBMS window ( Forms tab).

You can adjust the shape by pressing the Constructor button for the selected shape and dragging the corresponding controls with the mouse. Note that the creation of the main button form differs little from the described procedure.

Along with the main forms there are subordinate forms that do not have independent meaning.

Let's give a brief description of the main forms.

In the main forms, we select simple forms related to filling only one table, and composite forms that allow filling two or even three tables at once.

The schema of links of the database

Fig. 14.9. Database Linking Schema & "Learning Process"

Simple forms include "Laboratory", "Payment", "IPP", "Hostel", "Student".

Forms API and Hostel require the introduction of a parameter. Form Student made with bookmarks. The first tab Passport highlights the most frequently used and most important fields. Other bookmarks ( Relatives , Education, Personal Photos ) include fields that are used much less often.

Composite forms are the Group (allowing to fill in data about the group and specialty), "Study" (study and academic achievement), "Chair" (chair, teacher, laboratory), "Subject" (subject, study, academic achievement), "Enterprise (enterprise, STI, job bank), "Orders for the student" (orders and type of orders).

In a number of forms, the introduction of the code (group, student, etc.) is simplified by the introduction of a substitution field, which, in addition to the code, indicates the meaning of the corresponding concept. Substitution is performed after clicking the triangle in the corresponding field and in the form record.

When you enter data from other databases, you often have to convert them. To do this, use this sequence.

Required tables from other databases are imported into the current table. Import applies to Excel and Word tables. Then, from the imported tables, you compose the necessary query-selections with the characteristics of the fields in the table into which you want to enter the data. Next, the request-select is translated into an update request or a request-addition, less often into a join query.

For example, the Student BD Study process is populated with a query composed of the student table! another database.

The same method is used when using your own database tables, "Training process". An example of using your own data are queries that allow you to compute the fields in the "Group" table. and fill out the "Study" table.

From the technical point of view, it is possible to distinguish between the initial and the working filling.

Initial filling is carried out during the creation of the database, it is very labor intensive and requires the automation of the procedure. Automation is carried out by the system of intermediate queries and tables and can be carried out in a dialog or automatic mode. The first mode is used during the debugging of the database. In the second case, the system is controlled by macros or programs in the Visual Basic for Applications (VBA) language when data is created or changed in certain tables. Initial filling can be carried out in two stages: partial (to verify the performance of the database) and full filling.

Working filling is characterized by a much smaller dimension of the procedure updates ( additions , deletions, changes ) of the data. In this connection, the manual interactive mode of filling through forms or directly using tables is more widely used here. At the same time, large-dimension tables, most often tethered to time periods (for example, a semester), tables with computed fields should still be filled in automated mode. There are also procedures for archiving and automatic data changes (group names, course names).

Let's cover the filling questions in more detail.

Initial Fill

A number of tables ("Group", "Laboratory", "Department", "Teacher", "Specialty") have a small dimension. They are filled in manually in the dialog mode. Data is entered either directly into tables, or through forms.

However, in the Group table, there are computed fields for entering data into which you should use the query and table system for both the initial and the working filling.

The higher-dimensional tables are the Subject and "Study". Due to the absence of the electronic The source of the data is entered into them manually from the documents "Curriculum and Study schedule respectively. In the table Learning Data from the tables Teacher and Group .

Working filling

Here you should separate minor adjustments (one to several records) of data and the introduction of large amounts of data. It is advisable to talk only about the second type of filling, because the first ("manual") view is not difficult.

It's about the tables "Student", "Item", "Enterprise". The content of the derivatives tables ("IPP", "Group", "Profitability", "Dormitory", "Payment") should be changed through macros in automatic mode.

Significant changes should be expected in the tables "Student", "Subject", "Study", "Progress". If for the Student table, The replenishment procedure is easily automated, then for the tables "Item" and Learning the actual issue is the automation of the working procedure (in fact - the automation of the curriculum and the training schedule).

Manual and the filling of the table "Enterprise", as well as the introduction of assessments on tests and exams, remains. With the coverage of the database of all departments, the scores can be entered in the database table "The learning process" directly by teachers or secretaries of departments in the interactive mode.

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