✨ DB Nerdery Challenges Solutions II

src/answers.sql

@@ -1,15 +1,193 @@
 -- Your answers here:
 -- 1
-
+SELECT type, SUM(mount) AS total
+FROM  accounts
+group by type
 -- 2
-
+SELECT count(u.name) as user_w_least_two_accounts
+FROM users AS u
+         INNER JOIN accounts AS a ON u.id = a.user_id
+WHERE a.type = 'CURRENT_ACCOUNT'
+HAVING count(a.id) >= 2;
 -- 3
-
+SELECT id, mount
+FROM accounts
+ORDER BY mount DESC
+LIMIT 5;
 -- 4
+ DO
+    $$
+        DECLARE
+            account_balance RECORD;
+        BEGIN
+            FOR account_balance IN
+                WITH account_balances AS (SELECT u.name,
+                                                a.account_id,
+                                                a.mount        AS initial_mount,
+                                                COALESCE(SUM(
+                                                                CASE
+                                                                    WHEN m.type = 'TRANSFER' AND m.account_from = a.id
+                                                                        THEN -m.mount
+                                                                    WHEN m.type = 'TRANSFER' AND m.account_to = a.id
+                                                                        THEN m.mount
+                                                                    WHEN m.type = 'IN' AND m.account_from = a.id
+                                                                        THEN m.mount
+                                                                    WHEN m.type = 'OUT' AND m.account_from = a.id
+                                                                        THEN -m.mount
+                                                                    WHEN m.type = 'OTHER' AND m.account_from = a.id
+                                                                        THEN m.mount
+                                                                    ELSE 0
+                                                                    END
+                                                        ), 0) AS movement_total
+                                        FROM users AS u
+                                                INNER JOIN accounts AS a ON u.id = a.user_id
+                                                LEFT JOIN movements AS m ON a.id IN (m.account_from, m.account_to)
+                                        GROUP BY u.id, u.name, a.account_id, a.mount)
+                SELECT account_id,
+                    (initial_mount + movement_total) AS updated_balance
+                FROM account_balances
+
+                LOOP
+                    UPDATE accounts
+                    SET mount = account_balance.updated_balance
+                    WHERE account_id = account_balance.account_id;
+                END LOOP;
+        END
+    $$;
 
+    SELECT u.name || ' ' || u.last_name AS full_name, a.mount
+    FROM users AS u
+    INNER JOIN accounts AS a ON u.id = a.user_id
+    ORDER BY a.mount DESC
+    LIMIT 3;
 -- 5
+---A
+SELECT id, mount
+FROM accounts
+WHERE accounts.id = '3b79e403-c788-495a-a8ca-86ad7643afaf' OR accounts.id = 'fd244313-36e5-4a17-a27c-f8265bc46590';
+---B
+DO
+    $$
+        DECLARE
+            movement               RECORD;
+            updated_account_record RECORD;
+        BEGIN
+            INSERT INTO movements(id, type, account_from, account_to, mount)
+            VALUES (gen_random_uuid(),
+                    'TRANSFER',
+                    '3b79e403-c788-495a-a8ca-86ad7643afaf',
+                    'fd244313-36e5-4a17-a27c-f8265bc46590',
+                    50.75)
+            RETURNING * INTO movement;
 
--- 6
+            IF (SELECT mount FROM accounts WHERE id = movement.account_from) < movement.mount THEN
+                RAISE INFO 'Invalid movement: Insufficient balance in account %. Rolling back.', movement.account_from;
+                ROLLBACK;
+                RETURN;
+            END IF;
+
+            FOR updated_account_record IN
+                UPDATE accounts
+                    SET mount = CASE
+                                    WHEN id = movement.account_from THEN mount - movement.mount
+                                    WHEN id = movement.account_to THEN mount + movement.mount
+                        END
+                    WHERE id = movement.account_from
+                        OR id = movement.account_to
+                    RETURNING *
+                LOOP
+                    RAISE INFO 'Updated account %', updated_account_record.id;
+                END LOOP;
+
+            RAISE INFO 'Transaction successful';
+            COMMIT;
+        END
+    $$;
 
+---C
+DO
+    $$
+        DECLARE
+            record          RECORD;
+            accounts_record RECORD;
+        BEGIN
+            INSERT INTO movements(id, type, account_from, account_to, mount)
+            VALUES (gen_random_uuid(), 'OUT', '3b79e403-c788-495a-a8ca-86ad7643afaf', NULL, 731823.56)
+            RETURNING * INTO record;
+
+            UPDATE accounts
+            SET mount = mount - record.mount
+            WHERE id = record.account_from
+            RETURNING * INTO accounts_record;
+
+            IF accounts_record.mount < 0 THEN
+                RAISE NOTICE 'Invalid movement: Insufficient balance in account %. Rolling back.', record.account_from;
+                ROLLBACK;
+                RETURN;
+            END IF;
+
+            RAISE NOTICE 'Transaction successful: Movement ID %, Account ID %, New Balance %.',
+                record.id, accounts_record.id, accounts_record.mount;
+
+            COMMIT;
+        END
+    $$;
+---E
+INSERT INTO movements(id, type, account_from, account_to, mount)
+    VALUES (gen_random_uuid(), 'OUT', '3b79e403-c788-495a-a8ca-86ad7643afaf', NULL, 1000.05)
+    RETURNING * INTO record;
+---F
+RAISE NOTICE 'Transaction successful: Movement ID %, Account ID %, New Balance %.',
+        record.id, accounts_record.id, accounts_record.mount;
+--- G
+    SELECT id, mount
+    FROM accounts
+    WHERE id = 'fd244313-36e5-4a17-a27c-f8265bc46590';
+    COMMIT;
+-- 6
+WITH user_info AS (SELECT u.id                         AS user_id,
+                          u.name || ' ' || u.last_name AS fullname,
+                          u.email,
+                          u.date_joined,
+                          a.id                         AS account_id
+                   FROM users u
+                            INNER JOIN accounts a ON u.id = a.user_id
+                   WHERE a.id = '3b79e403-c788-495a-a8ca-86ad7643afaf')
+SELECT ui.fullname,
+       ui.email,
+       ui.date_joined,
+       m.type,
+       m.account_from,
+       m.account_to,
+       m.mount
+FROM user_info ui
+         LEFT JOIN movements m
+                   ON m.account_from = ui.account_id OR m.account_to = ui.account_id;
 -- 7
+WITH highest_account_mount AS (SELECT user_id, MAX(mount) AS max_mount
+                               FROM accounts
+                               GROUP BY user_id
+                               ORDER BY max_mount DESC
+                               LIMIT 1)
+
+SELECT u.name || ' ' || u.last_name AS full_name,
+       u.email,
+       ham.max_mount                AS total_money
+FROM users AS u
+         INNER JOIN highest_account_mount AS ham ON u.id = ham.user_id;
 
+-- 8
+WITH user_info AS (SELECT u.id, u.email, a.id AS account_id
+                   FROM users AS u
+                            INNER JOIN accounts AS a ON u.id = a.user_id
+                   WHERE u.email = 'Kaden.Gusikowski@gmail.com')
+SELECT DISTINCT ui.email,
+                m.id AS id_movement,
+                m.type,
+                m.account_from,
+                m.account_to,
+                m.mount,
+                m.created_at
+FROM movements m
+         INNER JOIN user_info ui ON m.account_from = ui.account_id OR m.account_to = ui.account_id
+ORDER BY m.type, m.created_at;