: 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
: Use CREATE TABLE IF NOT EXISTS or DROP TABLE IF EXISTS to ensure the script can be run multiple times without errors. wynajem.sql
: Use explicit INNER JOIN or LEFT JOIN syntax rather than comma-separated tables in the WHERE clause for better readability and maintenance . 4. Safety & Transactions : Check for NOT NULL constraints on essential
: 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 explicit INNER JOIN or LEFT JOIN
: 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 .
: Add inline comments ( -- ) or block comments ( /* ... */ ) to explain complex logic, such as how tax is calculated or how "available" status is determined.
: Replace SELECT * with explicit column names. This reduces unnecessary data transfer and prevents issues if the table schema changes .