Question

I just need a single MySQL line query for the following.

Lets say there are 2 simple tables: Class and Books

Class
ID--Name-----Students
1——KG———–20
2——Grade(3)—25
3——Grade(5)—30

Books
ID--ClassId--Title-------------Cost
1—–1————–Drawing——————5
2—–3————–History——————–25
3—–1————–A-to-Z——————–10
4—–2————–Alphabets—————20
5—–3————–Maths——————–15
6—–2————–English——————-30

Lets say:
What we only know is —–> ID of the Class
What we have to find is —> Book Cost of a class. (Books for Each Students In A Class)

Can I just have a Single Line of Query for it?

Answer 1

Try this:

In Single Line:

SELECT SUM(Class.Students * Books.Cost) AS BookCost  FROM Books INNER JOIN Class       ON Books.ClassId = Class.ClassId WHERE Books.ClassId = <CLASS-ID-VALUE>  GROUP BY Books.ClassId

With formatting:

SELECT SUM(Class.Students * Books.Cost) AS BookCost
  FROM Books INNER JOIN Class
   ON Books.ClassId = Class.ClassId
WHERE Books.ClassId = <CLASS-ID-VALUE>
GROUP BY Books.ClassId