1
vote
1answer
56 views

Database Normalization: A Case Of The NULLs [duplicate]

I'm trying to learn about proper database management and am having a hard time with designing a database that doesn't rely on NULLs. If you think I'm crazy for embarking on this, it is because of SQL ...
0
votes
2answers
107 views

Two nullable columns one required to have value

No-Explanation Question: Is there anyway to have a constrain of 2 null values that always requires 1 to have value ? For example two date columns both null but having at least 1 that requires to have ...
3
votes
2answers
9k views

Select column names whose entries are not null

I would like to have a list of those columns of a table that have at least one not-NULL data entries in them. In other words, I would like to get the column names for which the following returns at ...
3
votes
3answers
784 views

Empty LONGTEXT or NULL?

In my MySQL DB I have one field called html_contents that contains all the html to be shown in a webpage. Obviously the html could be huge, and certaintly bigger than 64KB, therefore I decided to use ...
2
votes
1answer
221 views

Null Values and Performance

I always try to build the database avoiding any NULL values in my tables, and I have successfully had done this so far. (Hey, I am very new to database design.) But still there are times when saving ...
11
votes
4answers
552 views

Reason to not use nullable number in Oracle?

Our company is interfacing with another software company for a joint project, and we were told that, if a particular value should not be displayed, we should pass in a -5000 (their arbitrary sentinel ...
2
votes
2answers
220 views

Proper use of NULL, and utilizing CHECK constraints for business logic vs stored procedures

This question regards the proper use of NULL and utilizing CHECK constraints for business logic vs stored procedures. I have the following tables setup. I normalized the tables to avoid using ...
4
votes
1answer
198 views

Is there some drawback to define SPARSE columns?

I have a table which has a lot of NULL values in columns. But some columns don't contain NULLs at all (although nullable). Is there some drawback to declare all of these columns as SPARSE?
41
votes
6answers
6k views

Why shouldn't we allow NULLs?

I remember reading this one article about database design and I also remember it said you should have field properties of NOT NULL. I don't remember why this was the case though. All I can seem to ...
6
votes
4answers
2k views

Finding empty columns of a table in PostgreSQL

What query would return the name of the columns of a table where all rows are NULL?