Database transactions

Database transactions group related local financial writes.

What it is

Database transactions group related local financial writes.

When to use it

Use a deliberate boundary for transfers and settlement updates.

Syntax

DB::transaction($callback);

Example

DB::transaction(function () use ($sourceId, $destinationId, $amountCents) {
    if ($amountCents <= 0 || $sourceId === $destinationId) {
        throw new InvalidArgumentException("Invalid transfer");
    }
    $changed = DB::table("accounts")->where("id", $sourceId)
        ->where("balance_cents", ">=", $amountCents)
        ->decrement("balance_cents", $amountCents);
    if ($changed !== 1) throw new RuntimeException("Debit rejected");
    $credited = DB::table("accounts")->where("id", $destinationId)
        ->increment("balance_cents", $amountCents);
    if ($credited !== 1) throw new RuntimeException("Destination missing");
});
// This focused example assumes prior authorization/currency checks.
// Add durable transfer/audit records and idempotency for a full operation.

Common mistakes

Validate account scope/currency and handle duplicates; this snippet alone is not a complete payment system.