Sequences in PL/SQL

Select the pseudo-column from the table DUAL.
select sequence.NEXTVAL  INTO variable from dual;

NULLS in PL/SQL:

NULLS in PL/SQL:

 - Represents unknown or inapplicable values
 - Never equal or not equal to anything
 - Most functions other than NVL, NVL2, CONCAT, REPLACE will return NULL when passed a Null
 - Use IS null OR IS NOT NULL to check NULL values

PL/SQL PRAGMA

PRAGMA -- Keyword used to give instructions to the PL/SQL compiler;

Types of PRAGMAS:

AUTONOMOUS_TRANSACTION:  Tells the compiler that the function, procedure,object method, trigger or top level block to execute in its own transaction.

EXCEPTION_INIT:
Tells the compiler to associate the specified error key with an identifier.

INLINE:
Tells the compiler whether calls to a subprogram should be replaced with a  copy of the subprogram.

RESTRICT_REFERENCES:
The degree to which a program does not read/write database tables and/or package variables.

SERIALLY_REUSABLE:
Tells the run time engine that package data should not persist between references.  This is used to reduce per user memory requirements when the package data is needed only for the duration of the call and not for the duration of the session.