Meeting #3 – January 2011 – Databases Homework Assignments Svetlin Nakov Telerik Corporation

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 sofia.bg/documents/Conspect0910.pdf sofia.bg/documents/Conspect0910.pdf sofia.bg/documents/Conspect0910.pdf  Follow strictly the IT test template: IT-Test- Questions-Template.pptx IT-Test- Questions-Template.pptxIT-Test- Questions-Template.pptx 3

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

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

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

9 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: Database Modeling with SQL Server (2)

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). Database Modeling with SQL Server (3)

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

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 (6)

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 Database Modeling with SQL Server (7)

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

31. Write a SQL to find the full name of each employee. 32. Write a SQL query to find the addresses of each employee (by his first and last name). Consider that the mail domain is telerik.com. s should look like The produced column should be named "Full 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

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, or 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 Order them in decreasing order by salary. 18

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

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

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

52. Write a SQL query to find the average salary in the department # 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

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

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

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

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

71. Write a SQL statement that changes the password to NULL for all users that have not been in the system since 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

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

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

81. 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. 82. Write a method that adds a new product in the products table in the Northwind database. To accomplish this use a parameterized SQL query. 83. 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 ( MB for example) and must be read and written in portions with streams. 31

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).

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.

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

 Homework solutions should be submitted at the following Web site:   Solutions should be packed in a single ZIP or RAR archive (up to 8 MB) 37

 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: 

Questions?