最近在寫(xiě)sqilte語(yǔ)句更新數(shù)據(jù)時(shí)發(fā)現(xiàn)個(gè)問(wèn)題，那就是Replace into執(zhí)行時(shí)居然會(huì)把id主鍵修改了。google了一下，原來(lái)Replace的原理是找到待修改的記錄后，整條刪除，然后插入新記錄。所以這個(gè)過(guò)程中，默認(rèn)的id主鍵會(huì)被修改。有時(shí)候這種結(jié)果并不是我們所想要的，應(yīng)該如何解決呢？
http://stackoverflow.com/questions/2717590/sqlite-upsert-on-duplicate-key-update這里有很好的討論。
個(gè)人覺(jué)得以下方法最好，摘抄如下。
INSERT OR REPLACE INTO page (id, name, title, content, author)
SELECT old.id, new.name, new.title, old.content, new.author
FROM ( SELECT
"about" AS name,
"About this site" AS title,
42 AS author
) AS new
LEFT JOIN (
SELECT id, name, content
FROM page WHERE name= "about"
) AS old ON new.name = old.name;