libpqxx
The C++ client library for PostgreSQL
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The built-in arithmetic types do not have inherent null values. More...
Static Public Member Functions | |
static bool | is_null (T const &value) |
Is value a null? | |
static T | null () |
Return a null value. | |
Static Public Member Functions inherited from pqxx::no_null< T > | |
static constexpr bool | is_null (T const &) noexcept |
Does a given value correspond to an SQL null value? |
Static Public Attributes | |
static bool | has_null |
Does this type have a null value? | |
static bool | always_null |
Is this type always null? | |
Static Public Attributes inherited from pqxx::no_null< T > | |
static constexpr bool | has_null |
Does TYPE have a "built-in null value"? | |
static constexpr bool | always_null |
Are all values of this type null? |
The built-in arithmetic types do not have inherent null values.
Not-a-Number values (or NaNs for short) behave a lot like an SQL null, but they are not nulls. A non-null SQL float can be NaN.
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staticnodiscard |
Return a null value.
Don't use this in generic code to compare a value and see whether it is null. Some types may have multiple null values which do not compare as equal, or may define a null value which is not equal to anything including itself, like in SQL.