主要学习和记录sql中索引的使用
1.批量在库里插入了27W条数据
2.EXPLAIN +sql语句的分析
EXPLAIN SELECT * FROM kucun_info WHERE kucunid = 3 -- const级别
EXPLAIN SELECT * FROM kucun_info WHERE shop_code = "XJ_001"
EXPLAIN SELECT * FROM kucun_info WHERE shop_name = "香蕉001"-- ref 级别
3.分析
-- 27W条数据
SET profiling = 1;
SELECT * FROM kucun_info WHERE shop_code = "XJ_001" -- 没加索引 0.086S
SELECT * FROM kucun_info WHERE shop_name = "香蕉001"-- 添加索引 0.015S
SELECT kucunid FROM kucun_info WHERE shop_code = "PT_001"
SELECT * FROM kucun_info WHERE shop_name = "葡萄001"
SHOW PROFILES; -- 查看执行sql语句的时间
可以分析出：27W条数据 加索引能快5倍
