SQL中的分区和空值

Question

I am working on mysql(wampserver) and i have made a simple database. i am writing a paper about nulls in databases and how to handle them,manage them. i have been working with all these functions ISNULL(IFNULL for mysql), COALESCE() etc, or replacing the "missing information" with unknown X and other ways. and i was wondering if partitioning helps. for example if i have NULLS in an order number(attribute) then if i move those tuples from my main table(customers) to another one(customers_1) will it help? i will have all my tuples with NULL in order number to the new table, and i think it will be easier to manage them, or even improve my database?

And another thing. is there any special way in relational algebra to manage nulls that are created from an outer join?

Thanks in advance

Answer 1

You can filter Nulls in the where clause. Eg:

  Where ColName IS NOT NULL