一、前言
MyBatis的update元素的用法與insert元素基本相同，因此本篇不打算重復了。本篇僅記錄批量update操作的
sql語句，懂得SQL語句，那么MyBatis部分的操作就簡單了。
注意：下列批量更新語句都是作為一個事務整體執行，要不全部成功，要不全部回滾。
二、MSSQL的SQL語句
WITH R AS（
SELECT 'John' as name, 18 as age, 42 as id
UNION ALL
SELECT 'Mary' as name, 20 as age, 43 as id
UNION ALL
SELECT 'Kite' as name, 21 as age, 44 as id
）
UPDATE TStudent SET name = R.name, age = R.age
FROM R WHERE R.id = TStudent.Id
三、MSSQL、ORACLE和MySQL的SQL語句 UPDATE TStudent SET Name = R.name, Age = R.age
from (
SELECT 'Mary' as name, 12 as age, 42 as id
union all
select 'John' as name , 16 as age, 43 as id
) as r
where ID = R.id
四、SQLITE的SQL語句
當條更新：
REPLACE INTO TStudent(Name, Age, ID)
VALUES('Mary', 12, 42)
批量更新：
REPLACE INTO TStudent(Name, Age, ID)
SELECT * FROM (
select 'Mary' as a, 12 as b, 42 as c
union all
select 'John' as a, 14 as b, 43 as b
) AS R
說明：REPLACE INTO會根據主鍵值，決定執行INSERT操作還是UPDATE操作。
五、總結
本篇突出MyBatis作為半自動ORM框架的好處了，全手動操控SQL語句怎一個爽字了得。但對碼農的SQL知識要求也相對增加了不少，倘若針對項目要求再將這些進行二次封裝那會輕松比少。
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