熱門標簽：北京外呼系統(tǒng)公司排名百度地圖標注員是干什么溫州人工外呼系統(tǒng)沈陽400電話是如何辦理貴陽智能電銷機器人官網(wǎng)外呼系統(tǒng)鄭州地圖標注付款了怎么找不到了外呼系統(tǒng)口號北京營銷外呼系統(tǒng)廠家1. LEFT OUTER JOIN:左外關(guān)聯(lián) SELECT e.last_name, e.department_id, d.department_name FROM employees e LEFT OUTER JOIN departments d ON (e.department_id = d.department_id); 等價于 SELECT e.last_name, e.department_id, d.department_name FROM employees e, departments d WHERE e.department_id=d.department_id(+); 結(jié)果為:所有員工及對應部門的記錄，包括沒有對應部門編號department_id的員工記錄。 2. RIGHT OUTER JOIN:右外關(guān)聯(lián) SELECT e.last_name, e.department_id, d.department_name FROM employees e RIGHT OUTER JOIN departments d ON (e.department_id = d.department_id); 等價于 SELECT e.last_name, e.department_id, d.department_name FROM employees e, departments d WHERE e.department_id(+)=d.department_id; 結(jié)果為:所有員工及對應部門的記錄，包括沒有任何員工的部門記錄。 3. FULL OUTER JOIN:全外關(guān)聯(lián) SELECT e.last_name, e.department_id, d.department_name FROM employees e FULL OUTER JOIN departments d ON (e.department_id = d.department_id); 結(jié)果為:所有員工及對應部門的記錄，包括沒有對應部門編號department_id的員工記錄和沒有任何員工的部門記錄。
