Method visit_update

lib/sqlalchemy/sql/compiler.py:6563–6711

(
        self,
        update_stmt: Update,
        visiting_cte: Optional[CTE] = None,
        **kw: Any,
    )

            return None

    def visit_update(
        self,
        update_stmt: Update,
        visiting_cte: Optional[CTE] = None,
        **kw: Any,
    ) -> str:
        compile_state = update_stmt._compile_state_factory(
            update_stmt, self, **kw
        )
        if TYPE_CHECKING:
            assert isinstance(compile_state, UpdateDMLState)
        update_stmt = compile_state.statement  # type: ignore[assignment]

        if visiting_cte is not None:
            kw["visiting_cte"] = visiting_cte
            toplevel = False
        else:
            toplevel = not self.stack

        if toplevel:
            self.isupdate = True
            if not self.dml_compile_state:
                self.dml_compile_state = compile_state
            if not self.compile_state:
                self.compile_state = compile_state

        if self.linting & COLLECT_CARTESIAN_PRODUCTS:
            from_linter = FromLinter({}, set())
            warn_linting = self.linting & WARN_LINTING
            if toplevel:
                self.from_linter = from_linter
        else:
            from_linter = None
            warn_linting = False

        extra_froms = compile_state._extra_froms
        is_multitable = bool(extra_froms)

        if is_multitable:
            # main table might be a JOIN
            main_froms = set(_from_objects(update_stmt.table))
            render_extra_froms = [
                f for f in extra_froms if f not in main_froms
            ]
            correlate_froms = main_froms.union(extra_froms)
        else:
            render_extra_froms = []
            correlate_froms = {update_stmt.table}

        self.stack.append(
            {
                "correlate_froms": correlate_froms,
                "asfrom_froms": correlate_froms,
                "selectable": update_stmt,
            }
        )

        text = "UPDATE "