怎么查看MySQL语句有没有用到索引？ 通过explain，如以下例子： EXPLAIN SELECT * FROM employees.titles WHERE emp_no='10001' AND title='Senior Engineer' AND from_date='1986-06-26'; idselect_typetablepartitionstypepossible_keyskeykey_lenreffilteredrowsExtra1SIMPLEtitlesnullconst