Method string_literal_to_sql

datafusion/sql/src/unparser/expr.rs:3098–3106

(&self, s: &str)

            }

            fn string_literal_to_sql(&self, s: &str) -> Option<ast::Expr> {
                if !s.is_ascii() {
                    Some(ast::Expr::value(ast::Value::NationalStringLiteral(
                        s.to_string(),
                    )))
                } else {
                    None
                }
            }
        }

        let dialect = MsSqlDialect;