Question

provide examples for the following:

Query Language:

SQL Queries:

Boolean Logic:

Answer 1

1.Query languages

• Query languages are used to retrieve information stored in a database or from an information system.
• examples of query languages are
  • SQL
  • SQL or structured query language is a query language used to retrieve information from a relational database such as Oracle.
  • XQuery
  • XQuery or XML query language is used to retrieve information from web-based documents

2. SQL queries

• SQL queries are used to retrieve and manage information from a relational database.
• Examples for SQL queries are
  • SELECT * STUDENT (This is a query that retrieves and display all the information stored in the table named STUDENT)
  • SELECT * FROM EMPLOYEE WHERE salary >10000 (Selects all the details from table employee where the salary of employee is greater than 10000
  • SELECT NAME FROM STUDENT WHERE RANK=1 (Select the name of student who is in the rank 1)

3.Boolean Logic

• In Boolean logic, all the operations are based upon two kinds of values, either TRUE or FALSE.
• The basic examples of boolean logic are the basic truth tables for Boolean operators AND, OR and NOT.
• AND operator (A.B)

A	B	A.B
T	T	T
T	F	F
F	T	F
F	F	F

• OR operator A+B

A	B	A+B
T	T	T
T	F	T
F	T	T
F	F	F

• NOR OPERATOR (A')

A	A'
T	F
F	T