https://www.startupcto.com/ 2026-04-27T20:54:13+00:00 https://www.startupcto.com/ https://www.startupcto.com/lib/tpl/scto/images/favicon.ico text/html 2020-11-21T22:39:03+00:00 Anonymous (anonymous@undisclosed.example.com) https://www.startupcto.com/backend-tech/sql/home?rev=1605998343 SQL sql index text/html 2023-06-27T04:52:39+00:00 Anonymous (anonymous@undisclosed.example.com) https://www.startupcto.com/backend-tech/sql/sql-notes?rev=1687841559 SQL Notes, Tips & Tricks * typecasting is done in SQL via double-colon :: (e.g var::integer) * As with other languages, NULL should represent non-existent data. In SQL, null is just represented as NULL. Columns can be set NOT NULL, which means every row must have some data for that column. In SQL, unlike PHP, NULL does not cast to zero. So NULL + 2 = NULL, and NULL < 2 evaluates to NULL, not TRUE.