: Ensure that currency fields (e.g., cena , kaucja ) use precise types like DECIMAL or NUMERIC rather than floating-point types to avoid rounding errors.
: Use CREATE TABLE IF NOT EXISTS or DROP TABLE IF EXISTS to ensure the script can be run multiple times without errors.
: Replace SELECT * with explicit column names. This reduces unnecessary data transfer and prevents issues if the table schema changes . wynajem.sql
: Verify that the rental data is normalized (e.g., separate tables for Klienci (Customers), Obiekty (Properties/Items), and Wynajmy (Rentals)). Ensure there is no redundant storage of rental rates in the transaction table if they can be retrieved via a JOIN from the primary item table .
: For operations involving multiple updates (e.g., marking an item as "rented" while creating a billing record), wrap the logic in a BEGIN TRANSACTION and COMMIT to maintain data integrity. : Ensure that currency fields (e
: Check for NOT NULL constraints on essential fields (dates, IDs) and CHECK constraints to ensure rental start dates are always before end dates. 2. Code Quality & Formatting
: Keywords should be in UPPERCASE (e.g., SELECT , FROM , WHERE ) to distinguish them from table and column names, which should follow a consistent snake_case or PascalCase naming convention. This reduces unnecessary data transfer and prevents issues
: Use descriptive aliases for tables (e.g., FROM Wynajmy AS w ) instead of single letters to improve clarity in multi-table joins. 3. Performance & Optimization