Database Reference
In-Depth Information
Letters A-Z, a-z
Digits 0-9
Symbols ~ ! @ # $ % * ( ) _ - + = | : ; “ ' < > , . ? / ^
Whitespace Tab, space, newline, carriage return
Characters are grouped together into lexical units, also called atomics of the language be-
cause they are the smallest individual components. A lexical unit in PL/ SQL is any of the
 Identifier
 Literal
 Delimiter
 Comment
8.4 PL/SQL Terminology
PL/SQL handles with the database and with the procedural world. Here are a few concepts
and terms we want to know.
Keyword: This topic uses the term keyword to mean a word that the language recognizes.
In PL/SQL, keywords include BEGIN, END, IF, and RETURN.
Identifier: An identifier is a name for a PL/SQL object, including any of the following:
 Constant or variable
 Exception
 Cursor
 Program name: procedure, function, package, object type, trigger, etc.  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 any
“whitespace” characters
Some examples of invented identifiers: Total_balance, Total_Cost.
Datatype : A name for a class of values. PL/SQL's built-in datatypes include NUMBER,
Variable: Variables are named temporary storage locations that support a particular data
type in your PL/SQL program. Some variables can hold only a single thing, like the number
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