Review Note

For the given schema, which of the following options best describes the results of the query: ∏_ID (ID F_MAX(balance) (σ_{balance<100,000} (depositor ∗ (account ∗ branch)))

A. Which depositors in the whole system have the maximum balance?
B. Which depositors in the whole system have the maximum balance under 100,000?
C. For every branch, which depositors have the maximum balance under 100,000 in that branch?
D. IDs of all customers with at least one account with balance under 100,000.
E. The query is invalid.

D - Account and branch fields are union joined through branch_name, then that is union joined to depositor through account_number. Now we have a table containing account_number, branch_name, amount, branch_name, branch_city, assets and ID. We then select only the rows with a balance lower than 100,000. Then we take the highest balance below 100,000 and output just the ID of that account.

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