Lightweight::SqlDynamicNumeric Struct Reference

A fixed-point decimal whose precision and scale are known only at run time. More...

#include <SqlDynamicNumeric.hpp>

Public Member Functions
constexpr bool	operator== (SqlDynamicNumeric const &other) const noexcept
constexpr bool	operator!= (SqlDynamicNumeric const &other) const noexcept
	Inequality, derived from operator==.
constexpr double	ToDouble () const noexcept
std::string	ToString () const
	Renders the exact decimal representation, including the trailing zeros implied by scale.

Static Public Member Functions
static constexpr std::optional< SqlDynamicNumeric >	FromString (std::string_view text, std::uint8_t precision, std::uint8_t scale) noexcept

Public Attributes
std::int64_t	unscaledValue = 0
	The value, scaled by 10^scale. 12.34 at scale 2 is stored as 1234.
std::uint8_t	precision = 0
	Total number of decimal digits the source column holds.
std::uint8_t	scale = 0
	Number of digits after the decimal point.

Detailed Description

A fixed-point decimal whose precision and scale are known only at run time.

This is the dynamic counterpart to SqlNumeric. Where SqlNumeric<Precision, Scale> fixes both at compile time, a value fetched into a SqlVariant learns its precision and scale from the result-set metadata, so they have to travel with the value.

The number is held exactly, as the unscaled integer value * 10^scale, and never passes through a binary floating-point type. That is the point of the type: DECIMAL(19, 4) — what MS SQL Server's money maps to — carries more significant digits than a double can represent, so reading such a column as double loses cents on large amounts.

Definition at line 239 of file SqlDynamicNumeric.hpp.

Member Function Documentation

operator==()

constexpr bool Lightweight::SqlDynamicNumeric::operator== ( SqlDynamicNumeric const &  other ) const

inlineconstexprnoexcept

Compares two values by mathematical magnitude, so the same number at different scales compares equal (1.50 at scale 2 equals 1.5 at scale 1).

Definition at line 252 of file SqlDynamicNumeric.hpp.

References scale, and unscaledValue.

operator!=()

constexpr bool Lightweight::SqlDynamicNumeric::operator!= ( SqlDynamicNumeric const &  other ) const

inlineconstexprnoexcept

Inequality, derived from operator==.

Definition at line 271 of file SqlDynamicNumeric.hpp.

ToDouble()

constexpr double Lightweight::SqlDynamicNumeric::ToDouble ( ) const

inlineconstexprnoexcept

Converts to a floating-point approximation.

Note

Lossy for values needing more significant digits than a double carries; read unscaledValue together with scale when exactness matters.

Definition at line 280 of file SqlDynamicNumeric.hpp.

References scale, and unscaledValue.

ToString()

std::string Lightweight::SqlDynamicNumeric::ToString ( ) const

inline

Renders the exact decimal representation, including the trailing zeros implied by scale.

Definition at line 294 of file SqlDynamicNumeric.hpp.

References scale, and unscaledValue.

Referenced by Lightweight::SqlDataBinder< SqlDynamicNumeric >::Inspect().

FromString()

static constexpr std::optional< SqlDynamicNumeric > Lightweight::SqlDynamicNumeric::FromString ( std::string_view  text, std::uint8_t  precision, std::uint8_t  scale  )

inlinestaticconstexprnoexcept

Parses an exact decimal literal, scaling it to scale.

Parameters

text	The decimal literal, as an ODBC driver renders a DECIMAL/NUMERIC column.
precision	Total digit count to record on the result.
scale	Fractional digit count to scale the value to.

Return values

std::nullopt

text is not a plain decimal literal, or does not fit the scale.

Definition at line 317 of file SqlDynamicNumeric.hpp.

References precision, scale, and unscaledValue.

Referenced by Lightweight::SqlDataBinder< SqlDynamicNumeric >::FromColumnLiteral().

Member Data Documentation

unscaledValue

std::int64_t Lightweight::SqlDynamicNumeric::unscaledValue = 0

The value, scaled by 10^scale. 12.34 at scale 2 is stored as 1234.

Definition at line 242 of file SqlDynamicNumeric.hpp.

Referenced by FromString(), operator==(), ToDouble(), and ToString().

precision

std::uint8_t Lightweight::SqlDynamicNumeric::precision = 0

Total number of decimal digits the source column holds.

Definition at line 245 of file SqlDynamicNumeric.hpp.

Referenced by FromString().

scale

std::uint8_t Lightweight::SqlDynamicNumeric::scale = 0

Number of digits after the decimal point.

Definition at line 248 of file SqlDynamicNumeric.hpp.

Referenced by FromString(), operator==(), ToDouble(), and ToString().

---

The documentation for this struct was generated from the following file:

• Lightweight/DataBinder/SqlDynamicNumeric.hpp