Linking Tables - Computer Science for Humanists

Linking tables

The table binding operation allows you to track errors, view related data, and correct related fields. For example, if in the absence of links we need to know the part of the speech of the wordform brought first we turn to the FREQUENCY table, sort it by the WORD field, find a lemma for the word = bring & quot ;, and then look at the Frequency_Leisure table. Sort it by the LEMMA field, find the part of the speech for the word bring = v.

For a small database like ours, this will require a little effort, but if the database contains hundreds of thousands of entries, for example a database on all Chekhov's works, even the simple task of finding a part of the speech becomes too cumbersome and time-consuming.

The inverse problem is to find all the verbs in the fairy tale COCK AND FATHERS - more complicated.

To solve this problem, you can add the LEMMA field and the Part_reference field to the WORDS table, but then the database will contain many duplicate records, which will increase the size of the database. Moreover, if we mistakenly defined a lemma, say, for the word after & quot ;, understanding it as a noun in the prepositional case, and then notice this error, we will have to correct all entries with the word after & quot ;. The mechanism MS Access allows you to perform the fix only once in the LEMMA field if the WORK TABLE, FREQUENCY, FREQUENCY () TA_LEMM and FREQ_GAM are linked.

Before defining the relationships, you must define the parent table (the main table) and the child table (the subordinate table) for each pair of linked tables. The relationship between them is a one-to-many, ratio. in the parent table, for example LEMM FREQUENCY, there is a unique entry with the LEMMA = drop field, and there are three such records in the child table, FREQUENCY.

In the parent table, you must set the LEMMA field (according to which the LEMM FREQUENCY table will be associated with the FREQUENCY table) Indexed field = Yes (Matches are not allowed). This operation is performed in the Designer mode (Figure 14.11).

Defining the properties of the field when binding tables

Fig. 14.11. Defining the field properties when binding tables

The same must be done for each parent-linked table (FREQUENCY GRAM, FREQUENCY_LEM, FREQUENCY_CLASS).

Any relationship links two fields that are in different tables. The FREQUENCY_TABLE and WORD tables are related by one-to-many relationships, i.e. 12 word usage boyar in the WORDS table are associated with one word "boyar" and " in the table FREQUENCY OF WORDS.

To define a relationship or relationship, do the following: Select the command sequence Work with databases - Show or hide - Data schema. The program Access opens a new tab Work with links on the ribbon. In this window, the links between any database tables are defined. Right-click in this window and select Add Table, then add the tables that will be linked.

We will consistently link the WORDS tables, WORK FREQUENCY, FREEDOM_LEMM and RequestGram. The sequence of actions for this is as follows.

1. To define a link, click on the WORD field in the WORK table and drag it to the field that you want to associate with it - the WORD field of the FREEDOM_FILE table. When you release the mouse button, the Change Link dialog box appears.

2. Check the box Ensure data connectivity. Also check the Cascade update for linked fields check box. It is not recommended to check the Cascade removal of linked fields check box, because you can permanently remove much of what may be required later.

3. Click the New button. This action will create a link connecting the two tables. The connection appears on the diagram as a line.

4. Perform the specified actions for all the relationships between the tables, as a result you get the connection scheme shown in Fig. 14.12.

Schema of links when linking tables

Fig. 14.12. Linking schema for linking tables

After defining the links, click the Data Schema tab, and then click Save.

Now you can change the Part of speech field in the FREQUENCY_GAME table, and these changes will also occur in the FrequencyLevel table. We will replace all the names of parts of speech with the corresponding United States terms (Figure 14.13).

Marking parts of speech in a table

Fig. 14.13. Marking parts of speech in a table

In this case, the Frequency_Gram table takes the following form (Figure 14.14).

Frequency_Gram Table

Fig. 14.14. Table Frequency_Gram

There is a very useful opportunity to view all records of a subordinate table that correspond to the value of the binding field in the main table. For example, we want to see all the lemmas with the grammatical attribute adverb & quot ;. In the FREQUENCY GRAM table, click on the left square with the plus sign on the left side of the record with the Part_repeat = adverb field. The result of the operation is shown in Fig. 14.15.

Table of adverbs in the fairy tale

Fig. 14.15. Table of adverbs in the fairy tale "The Rooster and the Millstones"

The sub-table that is opened can be sorted, edited, added and deleted in the same way. In addition, since the LEMM FREQUENCY table has its own subordinate table - FREQUENCY_CLUDE, you can expand the next sub-table by clicking on the + in the record of interest.

Reports are specialized database objects, similar in many ways to tables and queries. The report serves to represent the database data in a form suitable for printing. The easiest way to print one database table - is to use the means of MS Office •, click the Office (the round button in the upper right corner of any package MS Office), and then click Print. For large tables, you can narrow down mode in Table columns that are of no interest to a minimum, decrease font size, use landscape page orientation, and so forth.

An example of printing a fragment of a list of lemmas with the frequencies of all verbs from a fairy tale is shown in Fig. 14.16.

Fragment of the list of lemmas with frequencies of all verbs from the fairy tale

Fig. 14.16. A fragment of the list of lemmas with the frequencies of all the verbs from the fairy tale "The Rooster and the Millstones"

However, if you need a more significant print setup, you must create a special Report object. To create a report in Access , on the ribbon, select the sequence of commands Create - Reports - Report. A new tab with a simple automatically generated report appears on the screen. This report organizes information in the form of a table in which each field of the source table (or query) is in a separate column. The fields are located in the report from left to right in the same order as in the source table. You can delete unnecessary columns from the report by clicking on the column header by right-clicking the mouse and selecting Delete. You can also change the width of the columns by moving the mouse to the border of the column and sliding it to the left or right. To change the order of the columns, click on the column header and drag it to the new location without releasing the mouse button.

To change the formatting, change fonts, color and fill, select the column you want, on the ribbon, click the menu item Format, then Font, and select the font and its size. Using this method, you can change the way that table headers, column names, and data names are displayed. For more information on formatting, see the Access manuals. After the report is formatted, close the report object and save it if necessary.

Forms - an integral part of almost all databases, facilitating the work of users from the database. The forms provide an improved layout as compared to the tabular representation of the data. In the form, the necessary data is always in the user's field of vision. You can include in the form any text you need, i.e. you can insert explanations, add computed data, for example, calculate and display the average normalized frequency of occurrence of a given token in the text without having to create a separate query. Many tasks require adding records to several tables that are linked together. The form allows you to do this work in one place, without having to open two or more tables. Forms support controls - buttons, links, lists and other useful elements of the user interface.

Let's create the simplest form, allowing to receive lists of all words. Let's start with constructing a simple form that allows you to find all the sentences of a fairy tale containing a certain sequence of characters (the query in Figure 14.3). Choose from the transition area (the left side of the screen) the OFFER table. Go to the Create tab, click the Form button in it. The form with two fields of the OFFER: Code and Sent table appears on the screen. Go to the form mode (the left button in the ribbon from the top), where the width of the fields can be changed. To change the Field Width, move the cursor to the border of any form field, for example, the Sent field, and move it to the right or to the left. Reduce the width of the field by shifting the border to the right. Select both fields of the form by pressing Shift and clicking the left mouse button on each form field in turn. Clicking on any highlighted field, click the right mouse button and select Layout - Tabular from the drop-down menu. With the mouse, resize the fields by making the Code field small and the Sent field large. Now we formulate the selection conditions. Go to the Home tab - Sort - Filter. Click the Advanced button and select Change filter. In the form of the OFFER there will be empty Code and Sent fields, in which we can specify the selection conditions. In the Sent: InStr ([Sent]; Boyar ) field, click the Apply Filter button to see the first sentence of the tale that satisfies the query conditions (the sentence must be the word "boyar"). To view the following sentences that satisfy the same conditions, click the arrow (►) on the bottom line of the form or press the PageDown button on the keyboard. In Fig. 14.17 shows the result of using the form.

Using the Form function when creating a query

Fig. 14.17. Using the Form function when creating a query

Formatting the request, including changing the header, placing the fields, adding labels, is done in Design view and described in the Access manuals.

Conclusions

The chapter describes the use of DBMS Access to solve some typical philological tasks. The ways of input and editing of textual information, attaching OLE-objects, hyperlinks are considered. The necessity and the method of linking the tables are shown. In detail, operations are described for generating data query requests, including grouped queries and their representation in the form of SQL statements. The mechanism of sorting the query results is considered. All problems are analyzed by the example of processing short text of a fairy tale.

Also We Can Offer!

Other services that we offer

If you don’t see the necessary subject, paper type, or topic in our list of available services and examples, don’t worry! We have a number of other academic disciplines to suit the needs of anyone who visits this website looking for help.

How to ...

We made your life easier with putting together a big number of articles and guidelines on how to plan and write different types of assignments (Essay, Research Paper, Dissertation etc)