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Telerik School Academy
Meeting #3 – January 2011 – Databases
Homework Assignments
Svetlin Nakov
Telerik Corporation
www.telerik.com
Prepare IT Test
Questions
Prepare IT Test Questions
1.
Prepare at least 20 questions for preparation
for the National Olympiad's IT test
 Prepare at least one question for each category
from the official conspectus
 Try to create complex, non-trivial questions
 Categories are officially published at
http://edusoft.fmi.unisofia.bg/documents/Conspect0910.pdf
 Follow strictly the IT test template: IT-TestQuestions-Template.pptx
3
Relational Databases
Relational Databases
2.
Describe the database models do you know.
3.
Which are the main functions performed by a
Relational Database Management System
(RDBMS)?
4.
Define "table" in database terms.
5.
Explain the difference between a primary and a
foreign key.
6.
Explain the different kinds of relationships between
tables in relational databases.
7.
When is a certain database schema normalized?
What are the advantages of normalized databases?
5
Relational Databases (2)
8.
What are database integrity constraints and when
are they used?
9.
Point out the pros and cons of using indexes in a
database.
10.
What's the main purpose of the SQL language?
11.
What are transactions used for? Define their
responsibilities and explain their isolation levels.
6
Database Modeling
with SQL Server
Database Modeling
with SQL Server
12.
Download and install SQL Server Express. Install
also SQL Server Management Studio Express (this
could take some effort but be persistent).
13.
Connect to the SQL Server with SQL Server
Management Studio. Use Windows authentication.
14.
Create a new database Pubs and execute the script
install_pubs.sql to populate the DB contents.
15.
Attach the database Northwind (use the files
Northwind.mdf and Northwind.ldf) to
SQL Server and connect to it.
8
Database Modeling
with SQL Server (2)
16.
Backup the database Northwind into a file named
northwind-backup.bak and restore it as database
named North.
17.
Create a database named School and create the
following database schema in it:
9
Database Modeling
with SQL Server (3)
18.
Detatch the database School and attach it on
another computer. In case of name collision,
preliminary rename the database.
19.
Export the entire database School along with its
table data as SQL script. Use [Tasks] -> [Generate
Scripts]. Ensure that you have exported table data
rows (not only the schema).
10
Database Modeling
with SQL Server (4)
20.
Create the following database diagram in SQL
Server:
21.
Fill some sample data in the tables with SQL Server
Management Studio.
11
Database Modeling
with SQL Server (5)
22.
Typical universities have: faculties, departments,
professors, students, courses, etc. Faculties have
name and could have several departments. Each
department has name, professors and courses. Each
professor has name, a set of titles (Ph. D,
academician, senior assistant, etc.) and a set of
courses. Each course consists of several students.
Each student belongs to some faculty and to several
of the courses. Your task is to create a data model
(E/R diagram) for the typical university using SQL
Server Management Studio.
12
Database Modeling
with SQL Server (6)
23.
We should design a multilingual dictionary. We have
a set of words in the dictionary.
Each word can be in some language and can have
synonyms and explanations in the same language
and translation words and explanations in several
other languages.
The synonyms and translation words are sets of
words from the dictionary. The explanations are
textual descriptions.
Design a database schema (a set of tables and
relationships) to store the dictionary.
13
Database Modeling
with SQL Server (7)
24.
Add support in the previous database for storing
antonym pairs.
Add support for storing part-of-speech information
(e.g. verb, noun, adjective, …).
Add support for storing hypernym / hyponym chains
(e.g. tree  oak, pine, walnut-tree, …).
14
SQL Language
SQL
25.
What is SQL? What is DML? What is DDL? Recite the
most important SQL commands.
26.
What is Transact-SQL (T-SQL)?
27.
Start SQL Management Studio and connect to the
database TelerikAcademy. Examine the major tables
in the TelerikAcademy schema.
28.
Write a SQL query to find all information about all
departments.
29.
Write a SQL query to find all department names.
30.
Write a SQL query to find the salary of each
employee.
16
SQL (2)
31.
Write a SQL to find the full name of each employee.
32.
Write a SQL query to find the email addresses of
each employee (by his first and last name). Consider
that the mail domain is telerik.com. Emails should
look like “[email protected]". The produced
column should be named "Full Email Addresses".
33.
Write a SQL query to find all different employee
salaries.
34.
Write a SQL query to find all information about the
employees whose job title is “Sales Representative“.
35.
Write a SQL query to find the names of all
employees whose first name starts with "SA".
17
SQL (3)
36.
Write a SQL query to find the names of all
employees whose last name contains "ei".
37.
Write a SQL query to find the salary of all employees
whose salary is in the range [20000…30000].
38.
Write a SQL query to find the names of all
employees whose salary is 25000, 14000, 12500 or
23600.
39.
Write a SQL query to find all employees that do not
have manager.
40.
Write a SQL query to find all employees that have
salary more than 50000. Order them in decreasing
order by salary.
18
SQL (4)
41.
Write a SQL query to find the top 5 best paid
employees.
42.
Write a SQL query to find all employees along with
their address. Use inner join with ON clause.
43.
Write a SQL query to find all employees and their
address. Use equijoins (conditions in the WHERE
clause).
44.
Write a SQL query to find all employees along with
their manager.
45.
Write a SQL query to find all employees, along with
their manager and their address. Join the 3 tables:
Employees e, Employees m and Addresses a.
19
SQL (5)
46.
Write a SQL query to find all departments and all
region names, country names and city names as a
single list. Use UNION.
47.
Write a SQL query to find all the employees and the
manager for each of them along with the employees
that do not have manager. User right outer join.
Rewrite the query to use left outer join.
48.
Write a SQL query to find the names of all
employees from the departments "Sales" and
"Finance" whose hire year is between 1995 and 2000.
20
SQL (6)
49.
Write a SQL query to find the names and salaries of
the employees that take the minimal salary in the
company. Use a nested SELECT statement.
50.
Write a SQL query to find the names and salaries of
the employees that have a salary that is up to 10%
higher than the minimal salary for the company.
51.
Write a SQL query to find the full name, salary and
department of the employees that take the minimal
salary in their department. Use a nested SELECT
statement.
21
SQL (7)
52.
Write a SQL query to find the average salary in the
department #1.
53.
Write a SQL query to find the average salary in the
"Sales" department.
54.
Write a SQL query to find the number of employees
in the "Sales" department.
55.
Write a SQL query to find the number of all
employees that have manager.
56.
Write a SQL query to find the number of all
employees that have no manager.
57.
Write a SQL query to find all departments and the
average salary for each of them.
22
SQL (8)
58.
Write a SQL query to find the count of all employees
in each department and for each town.
59.
Write a SQL query to find all managers that have
exactly 5 employees. Display their first name and
last name.
60.
Write a SQL query to find all employees along with
their managers. For employees that do not have
manager display the value "(no manager)".
61.
Write a SQL query to find the names of all
employees whose last name is exactly 5 characters
long. Use the built-in LEN(str) function.
23
SQL (9)
62.
Write a SQL query to display the current date and
time in the following format "day.month.year
hour:minutes:seconds:milliseconds". Search in
Google to find how to format dates in SQL Server.
63.
Write a SQL statement to create a table Users.
Users should have username, password, full name
and last login time. Choose appropriate data types
for the table fields. Define a primary key column
with a primary key constraint. Define the primary
key column as identity to facilitate inserting records.
Define unique constraint to avoid repeating
usernames. Define a check constraint to ensure the
password is at least 5 characters long.
24
SQL (10)
64.
Write a SQL statement to create a view that
displays the users from the Users table that have
been in the system today. Test if the view works
correctly.
65.
Write a SQL statement to create a table Groups.
Groups should have unique name (use unique
constraint). Define primary key and identity column.
66.
Write a SQL statement to add a column GroupID to
the table Users. Fill some data in this new column
and as well in the Groups table. Write a SQL
statement to add a foreign key constraint between
tables Users and Groups tables.
25
SQL (11)
67.
Write SQL statements to insert several records in
the Users and Groups tables.
68.
Write SQL statements to update some of the
records in the Users and Groups tables.
69.
Write SQL statements to delete some of the records
from the Users and Groups tables.
70.
Write SQL statements to insert in the Users table
the names of all employees from the Employees
table. Combine the first and last names as a full
name. For username use the first letter of the first
name + the last name (in lowercase). Use the same
for the password, and NULL for last login time.
26
SQL (12)
71.
Write a SQL statement that changes the password
to NULL for all users that have not been in the
system since 10.03.2010.
72.
Write a SQL statement that deletes all users without
passwords (NULL password).
73.
Write a SQL query to display the average employee
salary by department and job title.
74.
Write a SQL query to display the minimal employee
salary by department and job title along with the
name of some of the employees that take it.
75.
Write a SQL query to display the town where
maximal number of employees work.
27
SQL (13)
76.
Write a SQL query to display the number of
managers from each town.
77.
Write a SQL to create table WorkHours to store
work reports for each employee (employee id, date,
task, hours, comments). Don't forget to define
identity, primary key and appropriate foreign key.
Issue few SQL statements to insert, update and
delete of some data in the table.
Define a table WorkHoursLogs to track all changes
in the WorkHours table with triggers. For each
change keep the old record data, the new record
data and the command (insert / update / delete).
28
SQL (14)
78.
Start a database transaction, delete all employees
from the 'Sales' department along with all
dependent records from the pother tables. At the
end rollback the transaction.
79.
Start a database transaction and drop the table
EmployeesProjects. Now how you could restore
back the lost table data?
80.
Find how to use temporary tables in SQL Server.
Using temporary tables backup all records from
EmployeesProjects and restore them back after
dropping and re-creating the table.
29
Data Access with ADO.NET
ADO.NET
81.
82.
83.
Write a program that retrieves from the Northwind
sample database in MS SQL Server all product
categories and the names of the products in each
category. Use SqlDataReader and a query to the
Categories and Products tables.
Write a method that adds a new product in the
products table in the Northwind database. To
accomplish this use a parameterized SQL query.
Create a DB in SQL Server to store a video clips
library. Write a program that reads and writes clips
to the DB. Have in mind that the clips will be big files
(100-200 MB for example) and must be read and
written in portions with streams.
31
ADO.NET Entity Framework
Entity Framework
84.
Using the Visual Studio Entity Framework designer
create a ObjectContext for the Northwind
database.
85.
Create a class with static methods which provides
functionality for inserting, modifying and deleting
customers. Write a testing class.
86.
Write a method using LINQ to find all customers who
have orders made in 1997 and shipped to Canada.
87.
Implement the previous by using a native SQL query
and executing it through the ObjectContext.
88.
Write a method that finds all the sales by specified
region and period (start / end dates).
Entity Framework (2)
89.
Create a database called NorthwindTwin with the
same structure as Northwind using the features from
ObjectContext. Find the API for schema generation
by .edmx mappings in MSDN or in Google.
90.
Try to open two different data contexts and perform
concurrent changes on the same records. What will
happen at SaveChanges()? How to deal with it?
91.
By inheriting the Employee entity class create a class
which allows employees to access their
corresponding territories as property of type
EntitySet<T>.
Entity Framework (3)
92.
Create a method that places a new order in the
Northwind database. The order should contain
several order items.
93.
Create a stored procedure in the Northwind
database for finding the total incomes for given
supplier name and period (start date, end date).
Implement a C# method that calls the stored
procedure and returns the retuned record set.
35
Submission Instructions
and Deadline
Submission Instructions
 Homework solutions
should be submitted at
the following Web site:
 http://nakov.devbg.org/schoolacademy-uploads/
 Solutions should be packed in a single ZIP or
RAR archive (up to 8 MB)
37
Further Instructions
 The deadline for the homework is:
 A week before the next training session
 Everybody is free to use help from friends,
teachers or Internet
 Submission of the same work by different
authors may result in a disqualification
 Ask your questions in the Telerik School
Academy official discussion group:
 http://groups.google.com/group/it-olymp
38
Homework Assignments
Questions?
http://schoolacademy.telerik.com