How to handle NULL in SQL скачать в хорошем качестве

How to handle NULL in SQL

The NULL value represents missing or not applicable information. But using it introduces three-valued logic. This can lead to surprising outcomes when handled incorrectly. This session covered the problems using NULL brings and how to avoid these. Highlights include: 00:30 - The problem with val = null 05:30 - Demo of problems and quirks with null 10:50 - Nulls in aggregate functions 16:30 - Nulls in check constraints 18:40 - Nulls in ORDER BY 20:50 - Why does null exist? 22:10 - Examples of not applicable/missing information and ways to change the schema to avoid null 32:40 - Handling end dates for currently active rows - null vs separate tables vs magic values 41:00 - The problem with magic values 45:00 - Situations where nulls can still appear when all columns are mandatory: outer joins, new columns, and window functions 47:30 - Demo of nulls in outer joins 48:45 - Nulls returned by window functions 50:00 - Mapping nulls to non-null values 55:40 - How to include nulls when searching for rows less than some value 1:00:30 - Summary Get the scripts for this session https://livesql.oracle.com/apex/lives... Improve Your SQL Skills - Databases for Developers: Next Level https://devgym.oracle.com/pls/apex/dg...