Identifiers in PL/SQL

PL/SQL identifiers are constants, variables, exceptions, procedures, cursors, and reserved words.
The identifiers consist of a letter optionally followed by more letters, numerals, dollar signs, underscores, and number signs and should not exceed 30 characters.
By default, identifiers are not case-sensitive. So you can use integer or INTEGER to represent a numeric value. You cannot use a reserved keyword as an identifier.

Delimiter Description
+, -, *, / Addition, subtraction/negation, multiplication, division
% Attribute indicator
Character string delimiter
. Component selector
(,) Expression or list delimiter
: Host variable indicator
, Item separator
Quoted identifier delimiter
= Relational operator
@ Remote access indicator
; Statement terminator
:= Assignment operator
<<, >>  Label delimiter (begin and end)
** Exponentiation operator
|| Concatenation operator
<>, ‘=, ~=, ^= Different versions of NOT EQUAL
<, >, <=, >= Relational operators
.. Range operator
Single-line comment indicator
/*, */ Multi-line comment delimiter (begin and end)