***** ## 單表優化 建表 ``` create table article( id int unsigned not null primary key auto_increment, author_id int unsigned not null, category_id int unsigned not null, views int unsigned not null, comments int unsigned not null, title varchar(255) not null, content text not null ); ``` 插入數據 ``` insert into article(`author_id`,`category_id`,`views`,`comments`,`title`,`content`) values (1,1,1,1,'1','1'), (2,2,2,2,'2','2'), (1,1,3,3,'3','3'); ``` 查詢category_id為1且comments大于1的情況下,views最多的article_id ## 雙表優化 建表 ~~~ 商品類別 create table class( id int unsigned not null primary key auto_increment, card int unsigned not null ); 圖書表 create table book( bookid int unsigned not null auto_increment primary key, card int unsigned not null ); ~~~ 驅動表的概念，mysql中指定了連接條件時，滿足查詢條件的記錄行數少的表為驅動表；如未指定查詢條件，則掃描行數少的為驅動表。mysql優化器就是這么粗暴以小表驅動大表的方式來決定執行順序的。