Literal 

A literal is an unknown data object that is defined fully by virtue of its value (specifies a non-NULL value, see data type). Literal values cannot be modified. A distinction is made between string literals and numeric literals.

Syntax

<literal> ::= <string_literal> | <numeric_literal>

string_literal, numeric_literal

String literals
'69190 Walldorf'
'Anthony Smith'

Numeric literals
+0.58498
1E160
-765E-04

Explanation

An apostrophe within a character string is represented by two successive apostrophes.

A string literal of the type '<character>...' or '' is only valid for a value referring to an alphanumeric column with the code attribute ASCII or EBCDIC. A hex_literal is only valid for a value referring to a column with the code attribute BYTE ( column definition).

A string literal ( string literal) of the type '' , x'' and X'' , and string literals that only contain blanks are not the same as the NULL value.