Challenge 2/ronald ris #51
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| -- | ||
| SELECT | ||
| TYPE ACCOUNT_TYPE, | ||
| ROUND(SUM(MOUNT)::NUMERIC, 2) MONEY_SUM |
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Nice to see you are using built-in functions such as round
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Thx this was to avoid problems with DOUBLE PRECISION and trailing number due to its precision scope.
Variable types matter!
| END AS mount | ||
| FROM movements | ||
| ) | ||
| UNION ALL |
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Asumme all movement incoming to an account is "1000", and starting mount on the same account is "1000".
UNION would take both rows as the same, while in reality the account should have 2000 as total balance!
This way I make sure to have all the mounts related to the account (account.from + account.to + account.startingMount) = account.finalBalance
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That's a pretty good explanation, with a nice example! Good job!
| -- 4 | ||
| -- I MAKE SURE I USE EVERY ACCOUNT BY UNION ALL! |
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I like this consideration. It's not implicit in the exercise, but it's good to have it!
src/answers.sql
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| RAISE NOTICE 'Account balance from % is %', account_id_b, account_balance_b; | ||
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| --b. Add a new movement with the information: from: 3b79e403-c788-495a-a8ca-86ad7643afaf make a transfer to fd244313-36e5-4a17-a27c-f8265bc46590 mount: 50.75 | ||
| IF account_balance_a < 50.75 THEN |
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You could have store 50.75 in a variable, so you don't need to update all places if you need to change the amount
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I resolved it using transfer_mount and out_mount.
A variable for each transfer and out mount.
DO $$
DECLARE
account_balance_a DOUBLE PRECISION;
account_balance_b DOUBLE PRECISION;
account_id_a UUID := '3b79e403-c788-495a-a8ca-86ad7643afaf';
account_id_b UUID := 'fd244313-36e5-4a17-a27c-f8265bc46590';
transfer_mount DOUBLE PRECISION := 50.75;
out_mount DOUBLE PRECISION := 20;
BEGIN| VALUES (gen_random_uuid(), 'TRANSFER', account_id_a,account_id_b, 50.75); | ||
| RAISE NOTICE 'Transfer % USD from % to % MADE SUCCESSFULLY!', 50.75, account_id_a, account_id_b; | ||
| END IF; | ||
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You could have add a savepoint here, to save your changes up to this point
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I could, but it'd lose the point of the transaction!
In case you may want to have a save point, I would most likely make 2 transactions.
This way it commits itself once the first is done or the second is finished.
TRANSACTION 1 for TRANSFER movement:
DO $$
DECLARE
account_balance_a DOUBLE PRECISION;
account_id_a UUID := '3b79e403-c788-495a-a8ca-86ad7643afaf';
account_id_b UUID := 'fd244313-36e5-4a17-a27c-f8265bc46590';
transfer_mount DOUBLE PRECISION := 50.75;
BEGIN
EXCEPTION
--
END;
$$;
TRANSACTION 2 for OUT movement:
DO $$
DECLARE
account_balance_a DOUBLE PRECISION;
account_id_a UUID := '3b79e403-c788-495a-a8ca-86ad7643afaf';
account_id_b UUID := 'fd244313-36e5-4a17-a27c-f8265bc46590';
out_mount DOUBLE PRECISION := 50.75;
BEGIN
EXCEPTION
--
END;
$$;
| SELECT money into account_balance_b | ||
| FROM get_accounts_final_balance() | ||
| WHERE account_id = account_id_b; | ||
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Not need due to the sintaxis I'm using.
DO $$
DECLARE
--
BEGIN
--
EXCEPTION
--
END;
$$;It treats the whole block as a transaction and only commit once its completely done
| END AS mount | ||
| FROM movements | ||
| ) | ||
| UNION ALL |
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That's a pretty good explanation, with a nice example! Good job!
This is my propose for solving the challenge problems.