关于知识点整理-mysql怎么查看优化器优化后的sql

CREATE TABLE t1 (m1 int, n1 char(1));
CREATE TABLE t2 (m2 int, n2 char(1));

INSERT INTO t1 VALUES(1, 'a'), (2, 'b'), (3, 'c');
INSERT INTO t2 VALUES(2, 'b'), (3, 'c'), (4, 'd');

SELECT *
FROM t1, t2
where t1.n1=t2.n2;