Trait InputParameter

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pub trait InputParameter: HasDataType + CElement { }

Expand description

Can be used to fill in a field value indicated by a placeholder (?) then executing an SQL statement.

§Supported input parameters

To bind a parameter its memory layout must be known to the ODBC driver. For some C-Types this is defined in the ODBC standard. Their rust equivalents are:

Some types have a memory layout known to the ODBC driver, but additional type information is required to bind them as parameters. You can use these together with WithDataType:

Note that the you may need to set the desired precision in the ADR record of the statement using a descriptor handle in order to bind a Numeric value which does not have scale 0. This is currently not supported in safe code. Consider binding large numeric values as Text.

§Support for idiomatic Rust types

Idomatic Rust types are supported through the IntoParameter trait. This trait can also be implemented for custom types in safe code.

Trait Implementations§

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impl CData for Box<dyn InputParameter>

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fn cdata_type(&self) -> CDataType

The identifier of the C data type of the value buffer. When it is retrieving data from the data source with fetch, the driver converts the data to this type. When it sends data to the source, the driver converts the data from this type.

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fn indicator_ptr(&self) -> *const isize

Indicates the length of variable sized types. May be zero for fixed sized types. Used to determine the size or existence of input parameters.

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fn value_ptr(&self) -> *const c_void

Pointer to a value corresponding to the one described by cdata_type.

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fn buffer_length(&self) -> isize

Maximum length of the type in bytes (not characters). It is required to index values in bound buffers, if more than one parameter is bound. Can be set to zero for types not bound as parameter arrays, i.e. CStr.

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impl CElement for Box<dyn InputParameter>

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fn assert_completness(&self)

Must panic if the parameter is not complete. I.e. the indicator of a variable length parameter indicates a value larger than what is present in the value buffer. Read more

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