Struct odbc_api::CursorImpl

pub struct CursorImpl<Stmt: BorrowMutStatement> { /* private fields */ }

Cursors are used to process and iterate the result sets returned by executing queries. Created by either a prepared query or direct execution. Usually utilized through the crate::Cursor trait.

Implementations

impl<S> CursorImpl<S> where
    S: BorrowMutStatement, 

pub unsafe fn new(statement: S) -> Self

Users of this library are encouraged not to call this constructor directly but rather invoke crate::Connection::execute or crate::Prepared::execute to get a cursor and utilize it using the crate::Cursor trait. This method is pubilc so users with an understanding of the raw ODBC C-API have a way to create a cursor, after they left the safety rails of the Rust type System, in order to implement a use case not covered yet, by the safe abstractions within this crate.

Safety

statement must be in Cursor state, for the invariants of this type to hold.

Trait Implementations

impl<S> Cursor for CursorImpl<S> where
    S: BorrowMutStatement, 

unsafe fn stmt_mut(&mut self) -> &mut Self::Statement

Provides access to the underlying statement handle.

fn bind_buffer<B>(
    self,
    row_set_buffer: B
) -> Result<RowSetCursor<Self, B>, Error> where
    B: RowSetBuffer, 

Binds this cursor to a buffer holding a row set.

fn next_row(&mut self) -> Result<Option<CursorRow<'_, Self::Statement>>, Error>

Advances the cursor to the next row in the result set.

impl<'o, S> Drop for CursorImpl<S> where
    S: BorrowMutStatement, 

fn drop(&mut self)

Executes the destructor for this type.

impl<S> ResultSetMetadata for CursorImpl<S> where
    S: BorrowMutStatement, 

type Statement = S::Statement

Statement type of the cursor. This is always an instantiation of crate::handles::Statement with a generic parameter indicating the lifetime of the associated connection.

fn stmt_ref(&self) -> &Self::Statement

Get a shared reference to the underlying statement handle. This method is used to implement other more high level methods like Self::describe_col on top of it. It is usually not intended to be called by users of this library directly, but may serve as an escape hatch for low level usecases.

fn describe_col(
    &self,
    column_number: u16,
    column_description: &mut ColumnDescription
) -> Result<(), Error>

Fetch a column description using the column index.

fn num_result_cols(&self) -> Result<i16, Error>

Number of columns in result set. Can also be used to see wether execting a prepared Statement (crate::Prepared) would yield a result set, as this would return 0 if it does not.

fn is_unsigned_column(&self, column_number: u16) -> Result<bool, Error>

true if a given column in a result set is unsigned or not a numeric type, false otherwise.

fn col_octet_length(&self, column_number: u16) -> Result<isize, Error>

Returns the size in bytes of the columns. For variable sized types the maximum size is returned, excluding a terminating zero.

fn col_display_size(&self, column_number: u16) -> Result<isize, Error>

Maximum number of characters required to display data from the column.

fn col_precision(&self, column_number: u16) -> Result<isize, Error>

Precision of the column.

fn col_scale(&self, column_number: u16) -> Result<isize, Error>

The applicable scale for a numeric data type. For DECIMAL and NUMERIC data types, this is the defined scale. It is undefined for all other data types.

fn col_name(&self, column_number: u16) -> Result<String, Error>

The column alias, if it applies. If the column alias does not apply, the column name is returned. If there is no column name or a column alias, an empty string is returned.

fn column_names(&self) -> Result<ColumnNamesIt<'_, Self>, Error>

Use this if you want to iterate over all column names and allocate a String for each one.

fn col_data_type(&self, column_number: u16) -> Result<DataType, Error>

Data type of the specified column.