MYSQL获取SQL的执行计划有哪些方式？
A desc + sql 语句
B 首先通过show processlist;获取线程ID；之后使用 EXPLAIN FOR CONNECTION 线程ID；获取执行计划。
C explain + sql 语句
D explain plan for + sql 语句
ABC
root@[sakila]08:47: >desc select * from city;
+----+-------------+-------+------------+------+---------------+------+---------+------+------+----------+-------+
| id | select_type | table | partitions | type | possible_keys | key | key_len | ref | rows | filtered | Extra |
+----+-------------+-------+------------+------+---------------+------+---------+------+------+----------+-------+
| 1 | SIMPLE | city | NULL | ALL | NULL | NULL | NULL | NULL | 600 | 100.00 | NULL |
+----+-------------+-------+------------+------+---------------+------+---------+------+------+----------+-------+
1 row in set, 1 warning (0.00 sec)
root@[sakila]08:53: >explain select * from city;
+----+-------------+-------+------------+------+---------------+------+---------+------+------+----------+-------+
| id | select_type | table | partitions | type | possible_keys | key | key_len | ref | rows | filtered | Extra |
+----+-------------+-------+------------+------+---------------+------+---------+------+------+----------+-------+
| 1 | SIMPLE | city | NULL | ALL | NULL | NULL | NULL | NULL | 600 | 100.00 | NULL |
+----+-------------+-------+------------+------+---------------+------+---------+------+------+----------+-------+
1 row in set, 1 warning (0.00 sec)
