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: 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 .
: 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 wynajem.sql
: Replace SELECT * with explicit column names. This reduces unnecessary data transfer and prevents issues if the table schema changes . : Verify that the rental data is normalized (e
: Ensure foreign keys (e.g., klient_id , obiekt_id ) and frequently filtered columns (like data_wynajmu ) are properly indexed to speed up search queries. : Ensure foreign keys (e
: Add inline comments ( -- ) or block comments ( /* ... */ ) to explain complex logic, such as how tax is calculated or how "available" status is determined.
: 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.
: 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
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