odbc_api

Trait ResultSetMetadata

Source 
pub trait ResultSetMetadata: AsStatementRef {
    // Provided methods
    fn describe_col(
        &mut self,
        column_number: u16,
        column_description: &mut ColumnDescription,
    ) -> Result<(), Error> { ... }
    fn num_result_cols(&mut self) -> Result<i16, Error> { ... }
    fn column_is_unsigned(&mut self, column_number: u16) -> Result<bool, Error> { ... }
    fn col_octet_length(
        &mut self,
        column_number: u16,
    ) -> Result<Option<NonZeroUsize>, Error> { ... }
    fn col_display_size(
        &mut self,
        column_number: u16,
    ) -> Result<Option<NonZeroUsize>, Error> { ... }
    fn col_precision(&mut self, column_number: u16) -> Result<isize, Error> { ... }
    fn col_scale(&mut self, column_number: u16) -> Result<isize, Error> { ... }
    fn col_name(&mut self, column_number: u16) -> Result<String, Error> { ... }
    fn column_names(&mut self) -> Result<ColumnNamesIt<'_, Self>, Error> { ... }
    fn col_data_type(&mut self, column_number: u16) -> Result<DataType, Error> { ... }
}
Expand description

Provides Metadata of the resulting the result set. Implemented by Cursor types and prepared queries. Fetching metadata from a prepared query might be expensive (driver dependent), so your application should fetch the Metadata it requires from the Cursor if possible.

See also: https://docs.microsoft.com/en-us/sql/odbc/reference/develop-app/result-set-metadata

Provided Methods§

Source

fn describe_col( &mut 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.
Source

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

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

See also: https://docs.microsoft.com/en-us/sql/odbc/reference/syntax/sqlnumresultcols-function

Source

fn column_is_unsigned(&mut 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.

column_number: Index of the column, starting at 1.

Source

fn col_octet_length( &mut self, column_number: u16, ) -> Result<Option<NonZeroUsize>, Error>

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

column_number: Index of the column, starting at 1.

Source

fn col_display_size( &mut self, column_number: u16, ) -> Result<Option<NonZeroUsize>, Error>

Maximum number of characters required to display data from the column. If the driver is unable to provide a maximum None is returned.

column_number: Index of the column, starting at 1.

Source

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

Precision of the column.

Denotes the applicable precision. For data types SQL_TYPE_TIME, SQL_TYPE_TIMESTAMP, and all the interval data types that represent a time interval, its value is the applicable precision of the fractional seconds component.

Source

fn col_scale(&mut 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.

Source

fn col_name(&mut 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.

Source

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

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

This is a wrapper around col_name introduced for convenience.

Source

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

Data type of the specified column.

column_number: Index of the column, starting at 1.

Dyn Compatibility§

This trait is not dyn compatible.

In older versions of Rust, dyn compatibility was called "object safety", so this trait is not object safe.

Implementors§