Why should you care?

ShopNest checkout must deduct stock and create Order in one atomic step — partial success would charge customers without inventory movement.

See it live — copy this example

Paste into a .NET project with EF Core packages, then run with LocalDB/SQL Server (dotnet ef / dotnet run).

await using var tx = await _context.Database.BeginTransactionAsync();
try
{
    var product = await _context.Products.FindAsync(productId);
    product!.StockQty -= qty;

    _context.Orders.Add(new Order { CustomerId = customerId, /* items */ });
    await _context.SaveChangesAsync();
    await tx.CommitAsync();
}
catch
{
    await tx.RollbackAsync();
    throw;
}

What happened?

• BeginTransactionAsync opens explicit transaction.
• SaveChangesAsync inside shares it.
• CommitAsync persists both stock change and order; RollbackAsync undoes both on failure.

Practice next

1. Wrap stock decrement + order insert in explicit transaction.
2. Force failure after SaveChanges and confirm rollback in SSMS.
3. Use Database.ExecuteSqlRaw within same transaction when needed.
4. Use IsolationLevel.Serializable only when phantom reads are unacceptable — measure lock impact.
5. Combine with execution strategy for retry on transient failures in Azure SQL.

Remember

Transactions ensure all-or-nothing commits. SaveChangesAsync is transactional by default. Explicit transactions coordinate multiple saves or raw SQL.

ShopNest checkout atomicity

Payment capture and order insert share one transaction — failure rolls back both.

Outcome: No paid orders without matching stock deduction rows.