查詢多個表放在一個集合中用union做連接

SELECT blood,BG,create_date,OGTT,flag FROM 
(
(SELECT "空腹血糖" AS blood,t.`BG`,t.create_date,t.`OGTT`,t.`BGFLAG` AS flag FROM xuetang AS t 
WHERE t.PERSON_ID=1101020142011000001 AND t.`BG` IS NOT NULL )UNION ALL

(SELECT "空腹血糖" AS blood, h.`BG`,h.`CREATE_DATE`,NULL,NULL AS flag FROM health_sugar AS h 
WHERE  h.PERSON_ID=1101020142011000001 AND h.`BG` IS NOT NULL )UNION ALL

(SELECT "空腹血糖" AS blood,c.`SC_FBG`,c.CREATE_DATE,NULL,NULL AS flag FROM common_manager AS c
WHERE c.PERSON_ID=1101020142011000001 AND c.`SC_FBG` IS NOT NULL )
) AS cc ORDER BY cc.create_date DESC;

用union做連接時應該注意列必須一樣多，如果一個表中有一列，另一個表沒有則可以用null代替

 

HQL不支持union，用sql實現，Query query = session.createSQLQuery();