LECTURE NOTES DBMS PART 1

     DATABASE MANAGEMENT SYSTEMS part 1

1. What are data and information, and how are they related in a database?

Data is recorded facts and figures, and information is knowledge derived from data. A

database stores data in such a way that information can be created.

2. What is Enterprise Resource Planning (ERP), and what kind of a database is used

in an ERP application?

Enterprise Resource Planning (ERP) is an information system used in manufacturing

companies and includes sales, inventory, production planning, purchasing and other business

functions. An ERP system typically uses a multiuser database.

3. What is a DBMS?

DBMS stands for Database Management System. A DBMS receives requests from applications

and translates those requests into actions on a specific database. A DBMS processes SQL

statements or uses other functionality to create, process and administer databases.

4. Why is a database considered to be "self-describing"?

In addition to the users' data, a database contains a description of its own structure. This

descriptive data is called "metadata."

5. Who is E.F. Codd, and why is he significant in the development of modern

database systems?

While working at IBM, E.F. Codd created the relational database model. A paper he published

in 1970 presented his ideas to the world at large. His work is the foundation for most of the

DBMSs currently in use, and thus forms the basis for database systems as we know and use

them today.

6. What is SQL, and why is it important?

SQL stands for Structured Query Language, and is the most important data processing

language in use today. It is not a complete programming language like Java or C#, but a data

sublanguage used for creating and processing database data and metadata. All DBMS products

today use SQL.

7. Write an SQL SELECT statement to display all the columns of the STUDENT table

but only those rows where the Grade column is greater than or equal to 90.

SELECT * FROM STUDENT WHERE Grade >= 90;

8. Name and briefly describe the five SQL built-in functions.

COUNT: computes the number of rows in a table. SUM: totals numeric columns. AVG:

computes the average value. MAX: obtains the maximum value of a column in a table. MIN:

obtains the minimum value of a column in a table.

9. Write an SQL SELECT statement to count the number of rows in STUDENT table

and display the result with the label NumStudents.

SELECT COUNT(*) AS NumStudents FROM STUDENT;

10. What is an SQL subquery?

An SQL subquery is a means of querying two or more tables at the same time. The subquery

itself is an SQL SELECT statement contained within the WHERE clause of another SQL SELECT

statement, and separated by being enclosed in parenthesis. Some subqueries have equivalent

SQL join structures, but correlated subqueries cannot be duplicated by a join..