The NaN (not a number) value is used to represent undefined calculational results.
Note that an infinity can only be stored in an unconstrained numeric column, because it notionally exceeds any finite precision limit.
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For example, Infinity plus any finite value equals Infinity, as does Infinity plus Infinity but Infinity minus Infinity yields NaN (not a number), because it has no well-defined interpretation. The infinity values behave as per mathematical expectations. The infinity values can alternatively be spelled inf and -inf. On input, these strings are recognized in a case-insensitive manner.
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When writing these values as constants in an SQL command, you must put quotes around them, for example UPDATE table SET x = '-Infinity'. These are adapted from the IEEE 754 standard, and represent “ infinity”, “ negative infinity”, and “ not-a-number”, respectively. If you're concerned about portability, always specify the precision and scale explicitly.) (The SQL standard requires a default scale of 0, i.e., coercion to integer precision. A column of this kind will not coerce input values to any particular scale, whereas numeric columns with a declared scale will coerce input values to that scale. Without any precision or scale creates an “ unconstrained numeric” column in which numeric values of any length can be stored, up to the implementation limits. The precision must be positive, the scale zero or positive. To declare a column of type numeric use the syntax: Integers can be considered to have a scale of zero.īoth the maximum precision and the maximum scale of a numeric column can be configured. So the number 23.5141 has a precision of 6 and a scale of 4. The scale of a numeric is the count of decimal digits in the fractional part, to the right of the decimal point. We use the following terms below: The precision of a numeric is the total count of significant digits in the whole number, that is, the number of digits to both sides of the decimal point. However, calculations on numeric values are very slow compared to the integer types, or to the floating-point types described in the next section. Calculations with numeric values yield exact results where possible, e.g., addition, subtraction, multiplication. It is especially recommended for storing monetary amounts and other quantities where exactness is required. The type numeric can store numbers with a very large number of digits. The following sections describe the types in detail.
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The numeric types have a full set of corresponding arithmetic operators and functions. The syntax of constants for the numeric types is described in Section 4.1.2. Up to 131072 digits before the decimal point up to 16383 digits after the decimal point
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