Setting null values vs Default or initial values in the Database?

Question

i am working on a system and i have set any field that might optional as Allow Null,, but this is causing me a lot of troubles especially when i am querying the data or perfoming some calculations from the database. So is it valid if i changed all the Allow null field to have initial values an restricting null values to be inserted into them, so example, to set the initial values for an integer to be 0 and string to be empty?

Answer 1

Hi,
You can implement business logic on db side or on app side.
Advantage and disadvantage of implementation business logic on DB side.
Advantages:
1.Don't require app server software version changes/compilations (Java, C, C++, C#...)
2.Stored procedures are stored directly in the db.
3.DBA can manage and optimize the stored procedures in flexible way; it'll be transparent for app server because the same remaining interface.
4.Avoidance of network traffic - the stored procedures can run directly within DB engine.
5.Encapsulation of business logic as API in the database.
6.Reports can be implemented like PL/SQL functions that return table data type. The functions can be called from application side - sort of API.
Disadvantages:
1.DB vendor specific, but when dealing with the same databases (for example Oracle) it's not relevant.
2.Require DB skills to write the procedures correctly: it will require time for a pure java/c/c++/c# programmer to understand the DB code and to write it in optimal (from db point of view) way.
3.If it's too complex business logic - the db side implementation can become too complex.
To overcome issue with null(s) please use NVL function.
Example:
drop table  TEST_TABLE;
create table TEST_TABLE(parameter varchar2(20), val number(10, 2));
insert into TEST_TABLE values ('A', 23.245);
insert into TEST_TABLE values ('B', null);
insert into TEST_TABLE values ('C', 123);
insert into TEST_TABLE values ('D', null);
select avg(nvl(val, 0)) from TEST_TABLE;Hope this will help.
Best Regards,
http://dba-star.blogspot.com/