What are the Bind Variables & Substitution Variables?

Bind Variables are also called host variables, which is accessed even after the PL/SQL block is executed.
It can be create using VARIABLE keyword and referenced with a preceding colon-:.

ex.
VARIABLE sal number;
begin
select salary into :sal from emp where emp_id = 11;
end;
/
select firstname , lastname from emp where salary = :sal;

Substitution Variables are used to get user input at run time to avoid hard-coding of values that we can provide run time also.
We can reference the same with in PL/SQL block with symbol ampersand-&.

VARIABLE sal number;
accept empid prompt 'provide emp id' 
declare
v_empid number := &empid; 
begin
select salary into :sal from emp where emp_id = v_empid;
end;
/
select firstname , lastname from emp where salary = :sal;

New PL/SQL Features and Enhancements in Oracle 11g

The new PL/SQL features and enhancements in Oracle 11g are as follows:

• Enhancements to regular expression built-in SQL functions
• SIMPLE_INTEGER, SIMPLE_FLOAT, and SIMPLE_DOUBLE datatypes
• CONTINUE statement
• Sequences in PL/SQL expressions
• Dynamic SQL enhancements
• More control over triggers
• Compound triggers
• Database resident connection pool
• Automatic subprogram inlining
• PL/Scope
• PL/SQL hierarchical profiler
• PL/SQL native compiler generates native code directly