Struct PreparedStatement

pub struct PreparedStatement { /* private fields */ }

A prepared query statement for use in a QueryRequest.

PreparedStatement encapsulates a prepared query statement. It includes state that can be sent to a server and executed without re-parsing the query.

The details of a prepared query are purposefully opaque, as its internal data and implementation may change over time.

PreparedStatement is only created by calling QueryRequest::execute() followed by QueryResult::prepared_statement().

The main purpose of a prepared statement is to parse a query for execution many times, with different variables. Here is a simple example using QueryRequest and PreparedStatement to insert a set of rows into a table (note: it may be more optimal to use WriteMultipleRequest for this specific case, this example is just to show the use of variables in prepared statetments):

let handle = Handle::builder().build().await?;
let prep_result = QueryRequest::new(
    "declare $id integer; $name string; insert into testusers(id, name) values($id, $name)",
)
.prepare_only()
.execute(&handle)
.await?;
let data = vec!["jane", "john", "jasper"];
let mut qreq = QueryRequest::new_prepared(&prep_result.prepared_statement());
for i in 0..data.len() {
    let id = (i as i32) + 1;
    qreq.set_variable("$id", &id)?;
    qreq.set_variable("$name", &data[i])?;
    let result = qreq.execute(&handle).await?;
    println!("Insert result = {:?}", result);
}

Trait Implementations

impl Clone for PreparedStatement

fn clone(&self) -> PreparedStatement

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for PreparedStatement

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Default for PreparedStatement

fn default() -> PreparedStatement

Returns the “default value” for a type.