[−][src]Trait odbc_api::Cursor

pub trait Cursor: Sized {
    fn describe_col(
        &self, 
        column_number: u16, 
        column_description: &mut ColumnDescription
    ) -> Result<(), Error>;
    fn num_result_cols(&self) -> Result<i16, Error>;
    unsafe fn fetch(&mut self) -> Result<bool, Error>;
    unsafe fn set_row_array_size(&mut self, size: u32) -> Result<(), Error>;
    unsafe fn set_num_rows_fetched(
        &mut self, 
        num_rows: &mut usize
    ) -> Result<(), Error>;
    unsafe fn set_row_bind_type(&mut self, row_size: u32) -> Result<(), Error>;
    fn unbind_cols(&mut self) -> Result<(), Error>;
    unsafe fn bind_col(
        &mut self, 
        column_number: u16, 
        target: &mut impl CDataMut
    ) -> Result<(), Error>;
    fn is_unsigned_column(&self, column_number: u16) -> Result<bool, Error>;
    fn bind_buffer<B>(
        self, 
        row_set_buffer: B
    ) -> Result<RowSetCursor<Self, B>, Error>
    where
        B: RowSetBuffer;
    fn col_type(&self, column_number: u16) -> Result<SqlDataType, Error>;
    fn col_concise_type(&self, column_number: u16) -> Result<SqlDataType, Error>;
    fn col_octet_length(&self, column_number: u16) -> Result<isize, Error>;
    fn col_display_size(&self, column_number: u16) -> Result<isize, Error>;
    fn col_precision(&self, column_number: u16) -> Result<isize, Error>;
    fn col_scale(&self, column_number: u16) -> Result<isize, Error>;
    fn col_name(
        &self, 
        column_number: u16, 
        buf: &mut Vec<u16>
    ) -> Result<(), Error>;
    fn application_row_descriptor(&self) -> Result<Description<'_>, Error>;

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

Cursors are used to process and iterate the result sets returned by executing queries.

Required methods

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

Fetch a column description using the column index.

Parameters

column_number: Column index. 0 is the bookmark column. The other column indices start with 1.
column_description: Holds the description of the column after the call. This method does not provide strong exception safety as the value of this argument is undefined in case of an error.

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

Number of columns in result set.

`unsafe fn fetch(&mut self) -> Result<bool, Error>`

Returns the next set of rows in the result set.

If any columns are bound, it returns the data in those columns. If the application has specified a pointer to a row status array or a buffer in which to return the number of rows fetched, fetch also returns this information. Calls to fetch can be mixed with calls to fetch_scroll.

Safety

Fetch dereferences bound buffers and is therefore unsafe.

`unsafe fn set_row_array_size(&mut self, size: u32) -> Result<(), Error>`

Sets the batch size for bulk cursors, if retrieving many rows at once.

Safety

It is the callers responsibility to ensure that buffers bound using bind_col can hold the specified amount of rows.

`unsafe fn set_num_rows_fetched( &mut self, num_rows: &mut usize ) -> Result<(), Error>`

Bind an integer to hold the number of rows retrieved with fetch in the current row set.

Safety

num_rows must not be moved and remain valid, as long as it remains bound to the cursor.

`unsafe fn set_row_bind_type(&mut self, row_size: u32) -> Result<(), Error>`

Sets the binding type to columnar binding for batch cursors.

Any Positive number indicates a row wise binding with that row length. 0 indicates a columnar binding.

Safety

It is the callers responsibility to ensure that the bound buffers match the memory layout specified by this function.

`fn unbind_cols(&mut self) -> Result<(), Error>`

Release all column buffers bound by bind_col. Except bookmark column.

`unsafe fn bind_col( &mut self, column_number: u16, target: &mut impl CDataMut ) -> Result<(), Error>`

Binds application data buffers to columns in the result set

column_number: 0 is the bookmark column. It is not included in some result sets. All other columns are numbered starting with 1. It is an error to bind a higher-numbered column than there are columns in the result set. This error cannot be detected until the result set has been created, so it is returned by fetch, not bind_col.
target_type: 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.
target_value: Pointer to the data buffer to bind to the column.
target_length: Length of target value in bytes. (Or for a single element in case of bulk aka. block fetching data).
indicator: Buffer is going to hold length or indicator values.

Safety

It is the callers responsibility to make sure the bound columns live until they are no longer bound.