小項目中數據庫的左連接應用與動態查詢

 

select a.*,p.id takeid,p.portname takeportname,p.cityname takecityname,
        t.id landid,t.cityname landcityname
         from airplane a LEFT JOIN airport p on a.takeid=p.id
         LEFT JOIN airport t on t.id=a.landid

 數據庫左連接、右連接、內連接、全連接筆記