SQL · Theory

Transaction

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Transaction

Don’t start Transaction with jargon. Start with fee payment. That is the whole point.

Keep Transaction small. Riya should finish fee payment in a few lines, not a 40-line dump.

Transaction exists so Riya can keep fee payment correct in accounts.

Transaction shows up in accounts. Name fee payment, not “a real-world scenario”.

If fee payment breaks under Transaction, check no COMMIT / no rollback on error first.

After Transaction, Riya should still remember no COMMIT / no rollback on error.

One breath for Transaction, then fee payment, then no COMMIT / no rollback on error. Sit down.

Exam tip

Board: fee payment. Dry-run Transaction. Name the trap: no COMMIT / no rollback on error.

Transaction — sample query

-- Transaction
CREATE TABLE demo (
  id INTEGER PRIMARY KEY,
  label TEXT NOT NULL,
  qty INTEGER DEFAULT 0
);
INSERT INTO demo (id, label, qty) VALUES
  (1, 'alpha', 2),
  (2, 'beta', 5);
SELECT label, qty FROM demo WHERE qty >= 2 ORDER BY qty DESC;

Transaction: create two demo rows, then SELECT qty >= 2 ordered. Say which labels come back.

Short notes

DefTransaction — Riya uses it for fee payment in accounts.
RuleTransaction → START TRANSACTION … COMMIT.
RememberTransaction + an index (accounts).
UseTransaction in accounts (fee payment).
TrapTransaction — no COMMIT / no rollback on error.
ExTransaction → fee payment.

-- Transaction CREATE TABLE demo ( id INTEGER PRIMARY KEY, label TEXT NOT NULL, qty INTEGER DEFAULT 0 ); INSERT INTO demo (id, label, qty) VALUES (1, 'alpha', 2), (2, 'beta', 5); SELECT label, qty FROM demo WHERE qty >= 2 ORDER BY qty DESC;

Transaction

Transaction — sample query

Short notes

Questions

Transaction

Transaction — sample query

Short notes

Questions