The name of any Oracle object (variable, constant, record,
cursor etc.) is known as an identifier. The following laws have to be followed
while working with identifiers:
1) An identifier cannot be declared twice in the same block.
2) The same identifier can be declared in two different
blocks.
If one follows the second law, the two identifiers are
unique and any change in one does not affect the other. An identifier can be declared
in a sub-block of another sub-block in which case it is local to that sub-block
alone.
To execute a PL/SQL program, one must follow the program
text itself by:
1) A line with a single dot (".") and then
2) A line with run
For example,
DECLARE
account number(5);
credit_limit number(9,2),
BEGIN
DECLARE,
account char(20);
newbalance number(9,2),
BEGIN
The identifiers available to this
block are
account-char(20), credit_limit,
new balance
END;
DECLARE
Old_balance
number(9,2);
BEGIN
/*The
identifiers available to this block are account number(5), credit_limit,
old_balance */
END;
/*The identifiers available here
are account nu n iber(5), credit limit*/
END:
