Oracle PL/SQL Programming, Third Edition

Identifiers

An identifier is a name for a PL/SQL object, including any of the following:

• Constant

• Scalar variable

• Composite variable (record or collection)

• Exception

• Procedure

• Function

• Package

• Type

• Cursor

• Reserved word

• Label

Default properties of PL/SQL identifiers are summarized below:

• Up to 30 characters in length

• Must start with a letter

• Can include $ (dollar sign), _ (underscore), and # (pound sign)

• Cannot contain spaces

If the only difference between two identifiers is the case of one or more letters, PL/SQL normally treats those two identifiers as the same.^[8] For example, the following identifiers are all considered by PL/SQL to be the same:

lots_of_$MONEY$
LOTS_of_$MONEY$
Lots_of_$Money$

The following strings are valid names of identifiers:

company_id#
primary_acct_responsibility
First_Name
FirstName
address_line1
S123456

The following identifiers are all illegal in PL/SQL:

1st_year                           -- Starts with numeral
procedure-name                     -- Contains invalid character "-"
minimum_%_due                      -- Contains invalid character "%"
maximum_value_exploded_for_detail  -- Name is too long
company ID                         -- Cannot have embedded spaces in name

Identifiers are the handles for objects in your program. Be sure to name your objects carefully so the names describe the objects and their uses. Avoid identifier names like X1 and temp; they are too ambiguous to mean anything to you or to anyone else reading your code.

Although rarely done in practice, you can actually break some of these rules by surrounding identifiers with double ...