Constants

A constant (also called a literal) specifies a value. Constants are classified as string constants or numeric constants. Numeric constants are further classified as integer, floating-point, decimal, or decimal floating-point. String constants are classified as character, graphic, or binary.

All constants have the attribute NOT NULL. A negative sign in a numeric constant with a value of zero is ignored, except for a decimal floating-point constant.

Constants have a built-in data type. Therefore, an operation that involves a constant and a distinct type requires that the distinct type be cast to the built-in data type of the constant or the constant be cast to the distinct type. For example, see Distinct type comparisons, which contains an example of casting data types to compare a constant to a distinct type.

Integer constants
An integer constant specifies an integer as a signed or unsigned number with a maximum of 19 digits that does not include a decimal point.
Floating-point constants
A floating-point constant specifies a double-precision floating-point number as two numbers separated by an E.
Decimal constants
A decimal constant is a signed or unsigned number of no more than 31 digits and either includes a decimal point or is not within the range of binary integers.
Decimal floating-point constants
A decimal floating-point constant specifies a decimal floating-point number as two numbers separated by an E. The first number can include a sign and a decimal point. The second number can include a sign but not a decimal point.
Character string constants
A character string constant specifies a varying-length character string. There are two forms of character string constant.
Binary string constants
A binary-string constant specifies a varying-length binary string.
Datetime constants
A datetime constant is a character string constant of a particular format.
Graphic string constants
A graphic string constant specifies a varying-length graphic string.

Parent topic: Language elements