[GENERAL] extend sql?

[xiapw]

Hello everyone,I want to konw how to extend the 
SQL.
For example,Create table temp [sec_level],sec_level means the 
secure level of the table that you have created,how to do this?
xiapw

[GENERAL] who has some document about extending postgresql

[xiapw]

Hi,who has some some document about extending postgresql,can 
you mail it to me?
Sting

[GENERAL] how to add a new column to system table

[xiapw]

I wanted to add a new column to system table(pg_database),but 
failed at last. Who know how to do this and can you tell me 
?

[GENERAL] I want to know how to improve the security of postgresql

[xiapw]

Hi guys,can you give me some advices about how to improve the 
security of postgresql?
Now I major in the security of postgresql and the destination 
is create a database with security level of B1(TCSEC),what should I do now,what 
program language should I use?
Thanks!
Sting