Answer to Question #229641 in Databases | SQL | Oracle | MS Access for Matthew

Question

1.If we apply the cross-product operation to these two instances of STUDENTS & BOOKS, what would be the resulting relation?

STUDENTS

Student_ID Student_Name Qualification

401 Andile HCIT

402 Carol DIT

403 Amber BSc

404 Bright HCIT

BOOKS

Book_ID Title Copy-right

101 Database fundamentals 2017

102 C++ how to program 2018

103 Simply Visual Basic 2019

104 OOP for beginners 2020

1.1 SELECT and RETURN all students with qualification HCIT from relations STUDENTS X BOOKS

1.2 Write a relational algebra expression using the symbolic notation for the given question in (1.1) above.

Answer 1

1. Combining each row of the left table with all rows of the right table. This type of connection is sometimes called a Cartesian product.

1.1 SELECT * FROM STUDENTS s

CROSS JOIN BOOKS b

WHERE Qualification LIKE 'HCIT'

RETURN:

Student_ID Student_Name Qualification Book_ID Title Copy-right

401 Andile HCIT 101 Database fundamentals 2017

401 Andile HCIT 102 C++ how to program 2018

401 Andile HCIT 103 Simply Visual Basic 2019

401 Andile HCIT 104 OOP for beginners 2020

404 Bright HCIT 101 Database fundamentals 2017

404 Bright HCIT 102 C++ how to program 2018

404 Bright HCIT 103 Simply Visual Basic 2019

404 Bright HCIT 104 OOP for beginners 2020

1.2 $\sigma$ _{qual = 'HCIT'}(STUDENTS * BOOKS)