mybaits

(整理)MyBatis入门教程（一）

https://www.cnblogs.com/kevin1990/p/6231122.html

https://www.cnblogs.com/hellokitty1/p/5216025.html#3591383

视频

https://edu.51cto.com/course/1354.html

mybaits入门

http://www.mybatis.org/mybatis-3/zh/getting-started.html

https://blog.csdn.net/isea533/article/details/73555400

https://www.baidu.com/link?url=HfPA9ZnTraLOT79irCSCJz_Aq_zebP9nJd1KqHBBEtX67yz_8PoxGXR8bomfg2gDVCTkhQ_IS-tkzwsgDXL-k_&wd=&eqid=e203282900688428000000055cfca243

1、此时mybatis中内置的参数_databaseId中保存了用户所指定的对应的数据库厂商标识。

<select id="selectUsrs" databaseId="mysql" resultType="com.heiketu.pojo.Users">
<if test="_databaseId == 'mysql'">
select * from usrs where id = 2
</if>
</select>

2、config。注册映射文件

3、#{id}值对应

4、别名去掉""

5、嵌套结果