☰ Contents · Computing

Chapter revision and test

Lessons 33–34 · 2 lessons · N. I. Taylaqov (general editor), A. B. Akhmedov, M. D. Pardayeva, A. A. Abdug‘aniyev, U. M. Mirsanov. Informatics and Information Technologies, Grade 10, 1st edition. “Extremum-Press”, Tashkent, 2017
33

Revision tasks

Textbook: pp. 75–76
GoalReviews the database chapter: database design, tables, keys, relationships, queries, forms, reports and calculations.
New words
design: deciding the tables, fields and keys before building · loyihalashintegrity: the data is correct and consistent · yaxlitlikcalculated field: a query column computed from other fields · hisoblanadigan maydonrevision: going over learned material again · takrorlash
Explanation

When revising the chapter, recall the job of each stage and where to do it. First the database is designed: tables, field types, primary keys and one-to-many relationships are planned in a notebook. Then the tables are built in Design View, properties such as Validation Rule and Required prevent mistakes, the tables are linked in the Relationships window and “Enforce Referential Integrity” keeps the data consistent. Queries are used for questions: Criteria, Between, Like, a parameter, a calculated field and Group By; a form is created for entering and viewing data and a report for printing. When checking, count each result by hand, for example the number of records or the mean value.

Worked examples
A sports club: Sports (SportID, SportName), Athletes (AthleteID, AthleteName, SportID), Results (ResultID, AthleteID, Points). Relationships: Sports – Athletes and Athletes – Results, both one-to-many; foreign keys: Athletes.SportID and Results.AthleteID.
One athlete’s points: 8, 7, 9. With Group By AthleteID and Sum the result is 24, with Avg it is 8. If three athletes produced 3, 2 and 4 results, the Results table holds 3+2+4 = 9 records.
Class activity

“Revision relay”: the class splits into groups; each group explains one stage of the chapter (design, table, relationship, query, form, report) in 2 minutes.

Practice
1
What kind of key is Results.AthleteID?
2
An athlete’s points are 6, 9, 3, 6. What is Avg?
3
Write a validation rule that keeps points between 0 and 10.
4
Why should a database be designed before the tables are built?