mysql查询优化

desc test

show index from test

EXPLAIN SELECT * FROM test

insert into test VALUES(7,6,4,4,7,2)

insert into test SELECT * from test

EXPLAIN SELECT A,B,D,E from test WHERE B BETWEEN 0 and 3 and C=1 and E>0 AND F=1 order by A,B,C,F

create INDEX INDEX_test on test(C,F,A,B,E,D)

drop INDEX INDEX_test on test

sql优化三星法则：

1.先列等值条件，且等值条件的列尽量相邻

2.再列order by列，order by列成本较高，尽量在第一个建立索引的时候包含列，利用B树索引排序。

3.列出区域查询的条件，以及要查询的所有列