pub struct Statement<'con, 'b, S, R> { /* private fields */ }
Expand description
A Statement
can be used to execute queries and retrieves results.
Implementations
sourceimpl<'a, 'b, S, R> Statement<'a, 'b, S, R>
impl<'a, 'b, S, R> Statement<'a, 'b, S, R>
sourcepub fn bind_parameter<'c, T>(
self,
parameter_index: u16,
value: &'c T
) -> Result<Statement<'a, 'c, S, R>>where
T: OdbcType<'c>,
T: ?Sized,
'b: 'c,
pub fn bind_parameter<'c, T>(
self,
parameter_index: u16,
value: &'c T
) -> Result<Statement<'a, 'c, S, R>>where
T: OdbcType<'c>,
T: ?Sized,
'b: 'c,
Binds a parameter to a parameter marker in an SQL statement.
Result
This method will destroy the statement and create a new one which may not outlive the bound parameter. This is to ensure that the statement will not derefernce an invalid pointer during execution.
Arguments
parameter_index
- Index of the marker to bind to the parameter. Starting at1
value
- Reference to bind to the marker
Example
let env = create_environment_v3().map_err(|e| e.unwrap())?;
let conn = env.connect("TestDataSource", "", "")?;
let stmt = Statement::with_parent(&conn)?;
let param = 1968;
let stmt = stmt.bind_parameter(1, ¶m)?;
let sql_text = "SELECT TITLE FROM MOVIES WHERE YEAR = ?";
if let Data(mut stmt) = stmt.exec_direct(sql_text)? {
// ...
}
sourcepub fn reset_parameters(self) -> Result<Statement<'a, 'a, S, R>>
pub fn reset_parameters(self) -> Result<Statement<'a, 'a, S, R>>
Releasing all parameter buffers set by bind_parameter
. This method consumes the statement
and returns a new one those lifetime is no longer limited by the buffers bound.
sourceimpl<'a, 'b> Statement<'a, 'b, Allocated, NoResult>
impl<'a, 'b> Statement<'a, 'b, Allocated, NoResult>
sourcepub fn prepare(
self,
sql_text: &str
) -> Result<Statement<'a, 'b, Prepared, NoResult>>
pub fn prepare(
self,
sql_text: &str
) -> Result<Statement<'a, 'b, Prepared, NoResult>>
Prepares a statement for execution. Executing a prepared statement is faster than directly executing an unprepared statement, since it is already compiled into an Access Plan. This makes preparing statement a good idea if you want to repeatedly execute a query with a different set of parameters and care about performance.
Example
let env = create_environment_v3().map_err(|e| e.unwrap())?;
let conn = env.connect("TestDataSource", "", "")?;
let stmt = Statement::with_parent(&conn)?;
let mut stmt = stmt.prepare("SELECT TITLE FROM MOVIES WHERE YEAR = ?")?;
fn print_one_movie_from<'a> (year: u16, stmt: Statement<'a,'a, Prepared, NoResult>) -> Result<Statement<'a, 'a, Prepared, NoResult>>{
let stmt = stmt.bind_parameter(1, &year)?;
let stmt = if let Data(mut stmt) = stmt.execute()?{
if let Some(mut cursor) = stmt.fetch()?{
println!("{}", cursor.get_data::<String>(1)?.unwrap());
}
stmt.close_cursor()?
} else {
panic!("SELECT statement returned no result set");
};
stmt.reset_parameters()
};
for year in 1990..2010{
stmt = print_one_movie_from(year, stmt)?
}
sourceimpl<'a, 'b> Statement<'a, 'b, Prepared, NoResult>
impl<'a, 'b> Statement<'a, 'b, Prepared, NoResult>
sourcepub fn num_result_cols(&self) -> Result<i16>
pub fn num_result_cols(&self) -> Result<i16>
The number of columns in a result set
Can be called successfully only when the statement is in the prepared, executed, or positioned state. If the statement does not return columns the result will be 0.
sourcepub fn describe_col(&self, idx: u16) -> Result<ColumnDescriptor>
pub fn describe_col(&self, idx: u16) -> Result<ColumnDescriptor>
Returns description struct for result set column with a given index. Note: indexing is starting from 1.
sourcepub fn execute(self) -> Result<ResultSetState<'a, 'b, Prepared>>
pub fn execute(self) -> Result<ResultSetState<'a, 'b, Prepared>>
Executes a prepared statement.
sourceimpl<'a, 'b, 'env> Statement<'a, 'b, Allocated, NoResult>
impl<'a, 'b, 'env> Statement<'a, 'b, Allocated, NoResult>
pub fn with_parent(ds: &'a Connection<'env>) -> Result<Self>
pub fn tables(self) -> Result<Statement<'a, 'b, Executed, HasResult>>
sourcepub fn exec_direct(
self,
statement_text: &str
) -> Result<ResultSetState<'a, 'b, Executed>>
pub fn exec_direct(
self,
statement_text: &str
) -> Result<ResultSetState<'a, 'b, Executed>>
Executes a preparable statement, using the current values of the parameter marker variables if any parameters exist in the statement.
SQLExecDirect
is the fastest way to submit an SQL statement for one-time execution.
sourceimpl<'a, 'b, S> Statement<'a, 'b, S, HasResult>
impl<'a, 'b, S> Statement<'a, 'b, S, HasResult>
sourcepub fn num_result_cols(&self) -> Result<i16>
pub fn num_result_cols(&self) -> Result<i16>
The number of columns in a result set
Can be called successfully only when the statement is in the prepared, executed, or positioned state. If the statement does not return columns the result will be 0.
sourcepub fn describe_col(&self, idx: u16) -> Result<ColumnDescriptor>
pub fn describe_col(&self, idx: u16) -> Result<ColumnDescriptor>
Returns description struct for result set column with a given index. Note: indexing is starting from 1.
sourcepub fn fetch<'c>(&'c mut self) -> Result<Option<Cursor<'c, 'a, 'b, S>>>
pub fn fetch<'c>(&'c mut self) -> Result<Option<Cursor<'c, 'a, 'b, S>>>
Fetches the next rowset of data from the result set and returns data for all bound columns.
sourcepub fn close_cursor(self) -> Result<Statement<'a, 'b, S, NoResult>>
pub fn close_cursor(self) -> Result<Statement<'a, 'b, S, NoResult>>
Call this method to reuse the statement to execute another query.
For many drivers allocating new statements is expensive. So reusing a Statement
is usually
more efficient than freeing an existing and alloctaing a new one. However to reuse a
statement any open result sets must be closed.
Only call this method if you have already read the result set returned by the previous
query, or if you do no not intend to read it.
Example
let env = create_environment_v3().map_err(|e| e.unwrap())?;
let conn = env.connect("TestDataSource", "", "")?;
let stmt = Statement::with_parent(&conn)?;
let stmt = match stmt.exec_direct("CREATE TABLE STAGE (A TEXT, B TEXT);")?{
// Some drivers will return an empty result set. We need to close it before we can use
// statement again.
Data(stmt) => stmt.close_cursor()?,
NoData(stmt) => stmt,
};
let stmt = stmt.exec_direct("INSERT INTO STAGE (A, B) VALUES ('Hello', 'World');")?;
//...