MySQL slow query optimization of the explain of the column meaning

Mysql>ExplainSelectCustomer_id,first_name,last_name fromcustomer;+----+-------------+----------+------+---------------+------+---------+------+------+-------+|Id|Select_type| Table |Type|Possible_keys| Key |Key_len|Ref|Rows|Extra|+----+-------------+----------+------+---------------+------+---------+------+------+-------+| 1 |Simple|Customer|  All | NULL | NULL | NULL | NULL | 599 | NULL |+----+-------------+----------+------+---------------+------+---------+------+------+-------+1Rowinch Set(0.00Sec

Returns the meaning of each column
Extra column needs to be aware of the return value
Using Filesort: When you see this, the query needs to be optimized.
Using temporary When you see this, you need to optimize,

http://www.imooc.com/video/3710

Notes

Mysql>ExplainSelect Max(payment_date) frompayment\g*************************** 1. Row***************************ID:1Select_type:simpleTable: Payment Type: AllPossible_keys:NULL          Key:NULLKey_len:NULLRef:NULLrows:16086Extra:NULL1Rowinch Set(0.00sec) MySQL> 

MySQL slow query optimization of the explain of the column meaning