Binding parameters

These functions are used to bind values to ODBC parameters. More...

Collaboration diagram for Binding parameters:

Modules
	Binding multiple non-string values
	Binds given values to given parameter placeholder number in the prepared statement.
	Binding multiple string values
	Binds given string values to parameter marker in prepared statement.

Functions
template<class T >
void	nanodbc::statement::bind (short param_index, T const *value, param_direction direction=PARAM_IN)
	Binds given value to given parameter placeholder number in the prepared statement.
template<class T >
void	nanodbc::statement::bind (short param_index, std::optional< T > const &value, param_direction direction=PARAM_IN)
	Binds a value that may be absent, an absent one being bound as null.
void	nanodbc::statement::bind_null (short param_index, std::size_t batch_size=1)
	Binds null values to the parameter placeholder number in the prepared statement.

Detailed Description

These functions are used to bind values to ODBC parameters.

Attention

When nanodbc is compiled as a library, bind() is only available for the types it is explicitly instantiated for in nanodbc.cpp. Using any other type compiles, because the declaration is visible here, but fails to link. The supported types are: bool, signed char, unsigned char, short, unsigned short, int, unsigned int, long int, unsigned long int, long long, unsigned long long, float, double, std::string::value_type, wide_string::value_type, date, time and timestamp. Binary data is bound through the std::vector<std::vector<std::uint8_t>> overloads, and strings through bind_strings().

bool is bound as ODBC's SQL_C_BIT, and only the overloads that carry no null information are available for it. The null_sentry overload takes T const* and the null flags overload takes bool const*, so for T=bool the two collapse into one signature that neither an explicit instantiation nor a call can choose between. Bind nullable booleans as a wider integral type instead.

Function Documentation

bind() [1/2]

template<class T >

void nanodbc::statement::bind	(	short	param_index,
		T const *	value,
		param_direction	direction = PARAM_IN
	)

Binds given value to given parameter placeholder number in the prepared statement.

If your prepared SQL query has any ? placeholders, this is how you bind values to them. Placeholder numbers count from left to right and are 0-indexed.

It is NOT possible to use these functions for batch operations as number of elements is not specified here.

Parameters

param_index	Zero-based index of parameter marker (placeholder position).
value	Value to substitute into placeholder.
direction	ODBC parameter direction.

Exceptions

database_error

bind() [2/2]

template<class T >

void nanodbc::statement::bind ( short  param_index, std::optional< T > const &  value, param_direction  direction = PARAM_IN  )

inline

Binds a value that may be absent, an absent one being bound as null.

This is the same as bind() followed by bind_null() for the absent case, written so that the caller need not tell the two apart. A copy of the value is taken, so the optional is free to go out of scope before the statement is executed.

std::optional<int> const age = lookup();
stmt.bind(0, age); // the value, or null where there is none

Parameters

param_index	Zero-based index of parameter marker (placeholder position).
value	The value to bind, or nothing to bind null.
direction	ODBC parameter direction.

Exceptions

database_error

See also

bind(), bind_null()

bind_null()

void nanodbc::statement::bind_null	(	short	param_index,
		std::size_t	batch_size = 1
	)

Binds null values to the parameter placeholder number in the prepared statement.

If your prepared SQL query has any parameter markers, ? (question mark) placeholders, this is how you bind values to them. Parameter markers are numbered using Zero-based index from left to right.

It is possible to use this function for batch operations.

Parameters

param_index	Zero-based index of parameter marker (placeholder position).
batch_size	The number of elements being bound.

Exceptions

database_error