Struct rusqlite::CachedStatement

pub struct CachedStatement<'conn> { /* fields omitted */ }

Cacheable statement.

Statement will return automatically to the cache by default. If you want the statement to be discarded, call discard() on it.

Methods

impl<'_> CachedStatement<'_>

pub fn discard(self)

Discard the statement, preventing it from being returned to its Connection's collection of cached statements.

Methods from Deref<Target = Statement<'conn>>

pub fn column_names(&self) -> Vec<&str>

Get all the column names in the result set of the prepared statement.

pub fn column_count(&self) -> usize

Return the number of columns in the result set returned by the prepared statement.

pub fn column_index(&self, name: &str) -> Result<usize>

Returns the column index in the result set for a given column name.

If there is no AS clause then the name of the column is unspecified and may change from one release of SQLite to the next.

Failure

Will return an Error::InvalidColumnName when there is no column with the specified name.

pub fn columns<'stmt>(&'stmt self) -> Vec<Column<'stmt>>

Returns a slice describing the columns of the result of the query.

pub fn execute<P>(&mut self, params: P) -> Result<usize> where
    P: IntoIterator,
    P::Item: ToSql, 

Execute the prepared statement.

On success, returns the number of rows that were changed or inserted or deleted (via sqlite3_changes).

Example

fn update_rows(conn: &Connection) -> Result<()> {
    let mut stmt = conn.prepare("UPDATE foo SET bar = 'baz' WHERE qux = ?")?;

    stmt.execute(&[1i32])?;
    stmt.execute(&[2i32])?;

    Ok(())
}

Failure

Will return Err if binding parameters fails, the executed statement returns rows (in which case query should be used instead), or the underling SQLite call fails.

pub fn execute_named(&mut self, params: &[(&str, &dyn ToSql)]) -> Result<usize>

Execute the prepared statement with named parameter(s). If any parameters that were in the prepared statement are not included in params, they will continue to use the most-recently bound value from a previous call to execute_named, or NULL if they have never been bound.

On success, returns the number of rows that were changed or inserted or deleted (via sqlite3_changes).

Example

fn insert(conn: &Connection) -> Result<usize> {
    let mut stmt = conn.prepare("INSERT INTO test (name) VALUES (:name)")?;
    stmt.execute_named(&[(":name", &"one")])
}

Note, the named_params macro is provided for syntactic convenience, and so the above example could also be written as:

fn insert(conn: &Connection) -> Result<usize> {
    let mut stmt = conn.prepare("INSERT INTO test (name) VALUES (:name)")?;
    stmt.execute_named(named_params!{":name": "one"})
}

Failure

Will return Err if binding parameters fails, the executed statement returns rows (in which case query should be used instead), or the underling SQLite call fails.

pub fn insert<P>(&mut self, params: P) -> Result<i64> where
    P: IntoIterator,
    P::Item: ToSql, 

Execute an INSERT and return the ROWID.

Note

This function is a convenience wrapper around execute() intended for queries that insert a single item. It is possible to misuse this function in a way that it cannot detect, such as by calling it on a statement which updates a single item rather than inserting one. Please don't do that.

Failure

Will return Err if no row is inserted or many rows are inserted.

pub fn query<P>(&mut self, params: P) -> Result<Rows> where
    P: IntoIterator,
    P::Item: ToSql, 

Execute the prepared statement, returning a handle to the resulting rows.

Due to lifetime restricts, the rows handle returned by query does not implement the Iterator trait. Consider using query_map or query_and_then instead, which do.

Example

fn get_names(conn: &Connection) -> Result<Vec<String>> {
    let mut stmt = conn.prepare("SELECT name FROM people")?;
    let mut rows = stmt.query(NO_PARAMS)?;

    let mut names = Vec::new();
    while let Some(row) = rows.next()? {
        names.push(row.get(0)?);
    }

    Ok(names)
}

Failure

Will return Err if binding parameters fails.

pub fn query_named(&mut self, params: &[(&str, &dyn ToSql)]) -> Result<Rows>

Execute the prepared statement with named parameter(s), returning a handle for the resulting rows. If any parameters that were in the prepared statement are not included in params, they will continue to use the most-recently bound value from a previous call to query_named, or NULL if they have never been bound.

Example

fn query(conn: &Connection) -> Result<()> {
    let mut stmt = conn.prepare("SELECT * FROM test where name = :name")?;
    let mut rows = stmt.query_named(&[(":name", &"one")])?;
    while let Some(row) = rows.next()? {
        // ...
    }
    Ok(())
}

Note, the named_params! macro is provided for syntactic convenience, and so the above example could also be written as:

fn query(conn: &Connection) -> Result<()> {
    let mut stmt = conn.prepare("SELECT * FROM test where name = :name")?;
    let mut rows = stmt.query_named(named_params!{ ":name": "one" })?;
    while let Some(row) = rows.next()? {
        // ...
    }
    Ok(())
}

Failure

Will return Err if binding parameters fails.

pub fn query_map<T, P, F>(&mut self, params: P, f: F) -> Result<MappedRows<F>> where
    P: IntoIterator,
    P::Item: ToSql,
    F: FnMut(&Row) -> Result<T>, 

Executes the prepared statement and maps a function over the resulting rows, returning an iterator over the mapped function results.

Example

fn get_names(conn: &Connection) -> Result<Vec<String>> {
    let mut stmt = conn.prepare("SELECT name FROM people")?;
    let rows = stmt.query_map(NO_PARAMS, |row| row.get(0))?;

    let mut names = Vec::new();
    for name_result in rows {
        names.push(name_result?);
    }

    Ok(names)
}

Failure

Will return Err if binding parameters fails.

pub fn query_map_named<T, F>(
    &mut self,
    params: &[(&str, &dyn ToSql)],
    f: F
) -> Result<MappedRows<F>> where
    F: FnMut(&Row) -> Result<T>, 

Execute the prepared statement with named parameter(s), returning an iterator over the result of calling the mapping function over the query's rows. If any parameters that were in the prepared statement are not included in params, they will continue to use the most-recently bound value from a previous call to query_named, or NULL if they have never been bound.

Example

fn get_names(conn: &Connection) -> Result<Vec<String>> {
    let mut stmt = conn.prepare("SELECT name FROM people WHERE id = :id")?;
    let rows = stmt.query_map_named(&[(":id", &"one")], |row| row.get(0))?;

    let mut names = Vec::new();
    for name_result in rows {
        names.push(name_result?);
    }

    Ok(names)
}

Failure

Will return Err if binding parameters fails.

pub fn query_and_then<T, E, P, F>(
    &mut self,
    params: P,
    f: F
) -> Result<AndThenRows<F>> where
    P: IntoIterator,
    P::Item: ToSql,
    E: From<Error>,
    F: FnMut(&Row) -> Result<T, E>, 

Executes the prepared statement and maps a function over the resulting rows, where the function returns a Result with Error type implementing std::convert::From<Error> (so errors can be unified).

Failure

Will return Err if binding parameters fails.

pub fn query_and_then_named<T, E, F>(
    &mut self,
    params: &[(&str, &dyn ToSql)],
    f: F
) -> Result<AndThenRows<F>> where
    E: From<Error>,
    F: FnMut(&Row) -> Result<T, E>, 

Execute the prepared statement with named parameter(s), returning an iterator over the result of calling the mapping function over the query's rows. If any parameters that were in the prepared statement are not included in params, they will continue to use the most-recently bound value from a previous call to query_named, or NULL if they have never been bound.

Example

struct Person {
    name: String,
};

fn name_to_person(name: String) -> Result<Person> {
    // ... check for valid name
    Ok(Person { name: name })
}

fn get_names(conn: &Connection) -> Result<Vec<Person>> {
    let mut stmt = conn.prepare("SELECT name FROM people WHERE id = :id")?;
    let rows =
        stmt.query_and_then_named(&[(":id", &"one")], |row| name_to_person(row.get(0)?))?;

    let mut persons = Vec::new();
    for person_result in rows {
        persons.push(person_result?);
    }

    Ok(persons)
}

Failure

Will return Err if binding parameters fails.

pub fn exists<P>(&mut self, params: P) -> Result<bool> where
    P: IntoIterator,
    P::Item: ToSql, 

Return true if a query in the SQL statement it executes returns one or more rows and false if the SQL returns an empty set.

pub fn query_row<T, P, F>(&mut self, params: P, f: F) -> Result<T> where
    P: IntoIterator,
    P::Item: ToSql,
    F: FnOnce(&Row) -> Result<T>, 

Convenience method to execute a query that is expected to return a single row.

If the query returns more than one row, all rows except the first are ignored.

Returns Err(QueryReturnedNoRows) if no results are returned. If the query truly is optional, you can call .optional() on the result of this to get a Result<Option<T>>.

Failure

Will return Err if the underlying SQLite call fails.

pub fn query_row_named<T, F>(
    &mut self,
    params: &[(&str, &dyn ToSql)],
    f: F
) -> Result<T> where
    F: FnOnce(&Row) -> Result<T>, 

Convenience method to execute a query with named parameter(s) that is expected to return a single row.

If the query returns more than one row, all rows except the first are ignored.

Returns Err(QueryReturnedNoRows) if no results are returned. If the query truly is optional, you can call .optional() on the result of this to get a Result<Option<T>>.

Failure

Will return Err if sql cannot be converted to a C-compatible string or if the underlying SQLite call fails.

pub fn parameter_index(&self, name: &str) -> Result<Option<usize>>

Return the index of an SQL parameter given its name.

Failure

Will return Err if name is invalid. Will return Ok(None) if the name is valid but not a bound parameter of this statement.

pub fn get_status(&self, status: StatementStatus) -> i32

Get the value for one of the status counters for this statement.

pub fn reset_status(&self, status: StatementStatus) -> i32

Reset the value of one of the status counters for this statement, returning the value it had before resetting.

Trait Implementations

impl<'_> Drop for CachedStatement<'_>

fn drop(&mut self)

Executes the destructor for this type.

impl<'conn> DerefMut for CachedStatement<'conn>

fn deref_mut(&mut self) -> &mut Statement<'conn>

Mutably dereferences the value.

impl<'conn> Deref for CachedStatement<'conn>

type Target = Statement<'conn>

The resulting type after dereferencing.

fn deref(&self) -> &Statement<'conn>

Dereferences the value.