7
votes
5answers
275 views

In retrospect, has it been a good idea to use three-valued logic for SQL NULL comparisons?

In SQL, NULL means "unknown value". Thus, every comparison with NULL yields NULL (unknown) rather than TRUE or FALSE. From a conceptional point of view, this three-valued logic makes sense. From a ...
0
votes
1answer
992 views

How to check for null in most sql's - “column is null” or “column = null” [closed]

I'm not sure of the right syntax to use. Is it select * from tlb where flag is NULL or select * from tlb where flag = NULL Is the answer the same for oracle, sqlserver and Postgres?
37
votes
11answers
27k views

SQL: empty string vs NULL value

I know this subject is a bit controversial and there are a lot of various articles/opinions floating around the internet. Unfortunatelly, most of them assume the person doesn't know what the ...