The banking system contains the main account table, which stores the accounts of all bank customers:
CREATE TABLE account (
id CHAR NOT NULL, -- account ID
client_id CHAR NOT NULL, -- identifier of the client, account holder
created DATE, -- account opening date
closed DATE, -- account closing date
amount BIGINT, -- account balance
PRIMARY KEY(id)
)
It is necessary to write SQL expressions for queries that return:
- list of open client accounts client_id=<client number> today
- list of clients who have closed all their accounts
- list of the most "valuable" clients for the bank, explaining how you define the "value" of a client
Given two ordered queues that may contain the same elements. Combine (Java) these queues into one ordered queue, eliminating duplicate elements.
Implement (Java) symmetric difference of two collections using Collection methods (addAll(), removeAll(), retainAll()).