sql
explain select * from city where ID>500 limit 10;
explain select `Name`,CountryCode,District from city where District='Utrecht';
explain select `Name`,CountryCode,District from city where ID=5;
explain select `Name`,CountryCode,District from city where ID<5;
explain select `Name`,CountryCode,District from city where CountryCode like 'NL_';
explain select `Name`,CountryCode,District from city where CountryCode='NLD' OR CountryCode='PHL';
explain select `Name`,CountryCode,District from city where CountryCode in('NLD','PHL');
explain select * from city where ID>500 limit 10;
explain select `Name`,CountryCode,District from city where District='Utrecht';
explain select `Name`,CountryCode,District from city where ID=5;
explain select `Name`,CountryCode,District from city where ID<5;
explain select `Name`,CountryCode,District from city where CountryCode like 'NL_';
explain select `Name`,CountryCode,District from city where CountryCode='NLD' OR CountryCode='PHL';
explain select `Name`,CountryCode,District from city where CountryCode in('NLD','PHL');
性能最快的方法是union联合查询
sql
explain
select `Name`,CountryCode,District from city where CountryCode='NLD'
union
select `Name`,CountryCode,District from city where CountryCode='PHL';