MySQL学习

EXPLAIN SELECT * FROM `city`;

#主键查询
EXPLAIN SELECT * FROM `city` where ID=5;

#索引查询
EXPLAIN SELECT * FROM `city` where CountryCode='NLD';

#主键范围查询
EXPLAIN SELECT * FROM `city` where ID>5 AND ID<20;

#非索引范围查询
EXPLAIN SELECT * FROM `city`where  Population>193238 AND Population<200000;