mysql中explain命令详解

1. EXPLAIN 命令的作用

   1. 模拟Mysql优化器是如何执行SQL查询语句的，从而知道Mysql是如何处理你的SQL语句的。分析你的查询语句或是表结构的性能瓶颈。

   2. mysql> explain select * from tb_user;
      +----+-------------+---------+------+---------------+------+---------+------+------+-------+
      | id | select_type | table  | type | possible_keys | key | key_len | ref | rows | Extra |
      +----+-------------+---------+------+---------------+------+---------+------+------+-------+
      | 1 | SIMPLE   | tb_user | ALL | NULL     | NULL | NULL  | NULL |  1 | NULL |
      +----+-------------+---------+------+---------------+------+---------+------+------+-------+

2. 参考链接