物化視圖:以前用的普通的視圖,普通視圖就是一段邏輯語句,對性能沒有任何的提升,也不能創建索引,而物化視圖會把視圖里查詢出來的數據在數據庫上建立快照,它和物理表一樣,可以創建 索引,主鍵約束等等,性能會有質的提升,但是其有缺點,會占用,可以設置它定時自動更新一次,也可以手動更新,當然也是可以設置及時更新的,但是會拉慢基表的增刪改查操作,在這里我只講思路,具體的話大家可以自己去研究。
--創建物化視圖,每天晚上22:00:00自動更新
create materialized view VM_PSNPERSONINFO
refresh force on demand start with sysdate next to_date( concat( to_char( sysdate+1,'dd-mm-yyyy'),' 22:00:00'),'dd-mm-yyyy hh24:mi:ss')
as
SELECT dt.personid, c.employeeid,d.unitcode,d.unitname,d.label,
dt.unitid,dt.startdate,dt.enddate
FROM (
SELECT DISTINCT b.personnelid personid,SUBSTR (a.effectdate, 1, 10) startdate,
MIN (CASE WHEN a.effectdate < b.effectdate THEN b.effectdate ELSE N'9999-99-99' END) AS enddate,
MIN (a.adjustresult) unitid
FROM psnadjust a LEFT JOIN psnadjust b
ON a.personnelid = b.personnelid
WHERE a.adjusttype = '2' AND b.adjusttype = '2'
GROUP BY b.personnelid, a.effectdate
) dt
INNER JOIN psnaccessioninfo c
ON c.personid = dt.personid
INNER JOIN orgstdstruct d
ON d.unitid = dt.unitid
ORDER BY employeeid, unitcode, startdate;
http://www.cnblogs.com/zhxhdean/archive/2011/05/16/2047795.html
http://blog.163.com/ybhjj2005@126/blog/static/561082842007235010598/
http://www.cnblogs.com/liuzhendong/archive/2011/10/10/2205744.html
