Code shared from the Rust Playground

playground.rs

use std::io;

struct Connection;

struct Handle<'c>(&'c Connection);

struct Statement<'c>(&'c Connection);

struct Rows<'c, 'l>(Statement<'c>, &'l mut Handle<'c>);

impl<'c> Handle<'c> {
    fn statement<'h>(&'h mut self,) -> Statement<'c> {
        Statement(self.0)
    }
    
    fn exec<'h>(&'h mut self, statement: Statement<'c>) -> Rows<'c, 'h> {
        Rows(statement, self)
    }
}

/*
    * crate any number of statements
    * run one query at a time
    * can't crate statement if query result is not consumed
    * can't run query if query result is not consumed
    
    So query result has to lock connection. But we need to have any number statements borrowing it before executing query.
*/

fn main() {
    let connection = Connection;
    let mut handle = Handle(&connection);
    
    let s1 = handle.statement();
    let r1 = handle.exec(s1);
    
    let s2 = handle.statement();
    let r2 = handle.exec(s2);
    
    drop(r1);
    drop(r2);
}