优化SQL语句的一般步骤②

1.定位执行效率比较低的sql语句

1） mysql> desc select * from t1\G;

2) mysql> explain select * from t1\G;

mysql> desc select * from t1\G;

*************************** 1. row ***************************

id: 1

select_type: SIMPLE

table: t1

type: ALL

possible_keys: NULL

key: NULL

key_len: NULL

ref: NULL

rows: 7

Extra: NULL

1 row in set (0.00 sec)