MySQL - accessing a table sum and compare to another table?
- by assignment_operator
This is for a homework assignment. I just plain don't understand how to do it.
The instructions for this particular question is:
List the branch name for all branches that have at least one
book that has at least 4 copies on hand.
Where the tables in question are:
Branch:
BranchName | BranchId
Henry Downtown | 1
16 Riverview | 2
Henry On The Hill | 3
Inventory:
BookId | BranchId | OnHand
1 | 1 | 2
2 | 3 | 4
3 | 1 | 8
4 | 3 | 1
5 | 1 | 2
6 | 2 | 3
From what I understand, I can get the number of OnHand per branch name with:
SELECT BranchName, SUM(OnHand)
FROM Branch B, Inventory I
WHERE B.BranchId = I.BranchId
GROUP BY BranchName;
but I don't get how I'd do the comparison between the sum of OnHand per branch and 4.
Any help would be appreciated, guys!
