/* temp table */
CREATE TEMPORARY TABLE temp_table
SELECT *
FROM your_table
WHERE your_condition;

UPDATE your_table
SET your_column = your_value
WHERE your_table.primary_key_column IN (
    SELECT primary_key_column
    FROM temp_table
);


/* Join - best way */
UPDATE Users
JOIN (
  SELECT Id
  FROM Users
  WHERE Id < 100
) AS t ON Users.Id = t.Id
SET Valid = 0;