Constructs a SQL query from a Diesel AST.
The only reason you should ever need to interact with this trait is if you
are extending Diesel with support for a new backend. Plugins which extend
the query builder with new capabilities will interact with
sql to the end of the query being constructed.
fn push_identifier(&mut self, identifier: &str) -> QueryResult<()>
identifier, and add it to the end of the query being
fn push_bind_param(&mut self)
Add a placeholder for a bind parameter to the end of the query being constructed.
Returns the constructed SQL query.