Go - Transactions & Migrations

Transactions & Migrations

Group database operations atomically using transactions and evolve schema safely with migrations.

Transactions

tx, err := db.Begin()
if err != nil { /* handle */ }
_, err = tx.ExecContext(ctx, "INSERT INTO accounts(id,balance) VALUES(?,?)", 1, 100)
if err != nil { tx.Rollback(); /* handle */ }
_, err = tx.ExecContext(ctx, "UPDATE accounts SET balance=balance-? WHERE id=?", 10, 1)
if err != nil { tx.Rollback(); /* handle */ }
if err := tx.Commit(); err != nil { /* handle */ }

Migrations (CLI)

Use a migration tool (e.g., golang-migrate) to version schema changes.

// CLI example (bash)
// migrate create -ext sql -dir db/migrations add_users
// migrate -path db/migrations -database $DSN up

Common errors

• Forgetting to set proper isolation level when needed.
• Not using context.Context with deadlines for long operations.

Practice

• Create an idempotent migration to add an index and verify down scripts.

Quick quiz

1. What happens if you forget to Commit or Rollback?