# 总查询 

EXPLAIN SELECT * FROM `city`;

# 范围查询

EXPLAIN SELECT * from `city` where ID>5 and ID<20;

#主键查询 

EXPLAIN SELECT * from `city` where ID=5;

# 索引查询 

EXPLAIN SELECT * from `city` where CountryCode='NLD';

 # 普通索引

EXPLAIn SELECT * from `city` where Name='haag';

 

EXPLAIN SELECT * from `city` where CountryCode in ('NLD','DZA');