Another common pitfall to avoid when optimizing SQL queries for NULL values is using the NOT IN operator with a subquery that contains NULL values. For example, suppose you want to find the ...

We have just graduated from the SQL 101 class so we will be very clever and retrieve the records that are NOT NULL. Thus, we write the following query: SELECT ExampleID, FixedAlphaVal FROM Example ...

To do this in SQL, you specify a column as NOT NULL. NOT NULL tells SQL to only allow a row to be added to a table if there is a value for the field. For example, NOT NULL assigned to the field ...